scholarly journals Weather & weather systems at Schirmacher Oasis (Maitri) during recent two decades - A review

MAUSAM ◽  
2021 ◽  
Vol 62 (4) ◽  
pp. 513-534
Author(s):  
AJIT TYAGI ◽  
U.P. SINGH ◽  
M. MOHAPATRA
Keyword(s):  
Winter Season ◽  
Leading Edge ◽  
Lower Latitude ◽  
Katabatic Winds ◽  
Air Masses ◽  
Blocking Anticyclone ◽  
Pressure Centre ◽  
Schirmacher Oasis ◽  
Slow Moving ◽  
High Pressure Centre

Indian Antarctic station Maitri experiences varying external influences from interior of east Antarctica as well as moving depressions and cyclones along the coast. The relative position of circumpolar trough and strengthening of high pressure centre near pole influences variation of atmospheric pressure at Maitri. The diurnal, daily and seasonal variation of temperature mainly depend upon moving pressure systems, katabatic winds, change of solar insulation with change of seasons, reflectivity from clouds and snow surface. The katabatic winds prevail over Maitri which is highly directional from South- East sector due to increase of slope towards south. The blizzards are main weather at Maitri, fog and white out are occasional phenomena. The precipitation is mostly in form of snowfall but rain is very rare at Maitri. Heavy or moderate snowfall indicative of active front leading edge of warm air masses being transported southwards. Strong temperature variant near Schirmacher oasis give precipitation in form of snow. Fog occurred due to slow movement of relatively warm air from lower latitude over the colder surface. Winter season witnessed more snowfall accumulation at Maitri than other season. During summer rise of temperature accompanied with absorption of latent heat by ice pellets in low level of atmosphere results precipitation in form of water droplets. Highest number of blizzards occurs during winter season whereas lowest number of blizzards occurs during summer season. Normally due to cyclonic activities, warm air masses transported towards the Schirmacher oasis which causes rise of temperature at Maitri. Longer duration of the blizzards over the station depends upon strength of slow moving blocking anticyclone situated east of Maitri at lower latitude. Tremendous fluctuation of atmospheric electric field observed before onset is a pre-indication of commencement of blizzards.

Inflight icing data gathering during routine flight operations — a case study

2001 ◽  
Vol 105 (1051) ◽  
pp. 501-516 ◽  
Author(s):  
A. P. Brown
Keyword(s):  
Data Gathering ◽  
Winter Season ◽  
Leading Edge ◽  
General Aviation ◽  
Data Sets ◽  
Large Droplet ◽  
Event Data ◽  
Flight Operations ◽  
Lower Corner

Abstract For the purpose of the design and certification of inflight icing protection systems for transport and general aviation aircraft, the eventual re-definition/expansion of the icing environment of FAR 25/JAR 25, Appendix C is under consideration. Such a re-definition will be aided by gathering as much inflight icing event data as reasonably possible, from widely-different geographic locations. The results of a 12-month pilot programme of icing event data gathering are presented. Using non-instrumented turboprop aircraft flying upon mid-altitude routine air transport operations, the programme has gathered observational data from across the British Isles and central France. By observing a number of metrics, notably windscreen lower-corner ice impingement limits, against an opposing corner vortex-flow, supported by wing leading edge impingement limits, the observed icing events have been classified as ‘small’, ‘medium’ or ‘large’ droplet. Using the guidance of droplet trajectory modelling, MVD values for the three droplet size bins have been conjectured to be 15, 40 and 80mm. Hence, the ‘large’ droplet category would be in exceedance of FAR/JAR 25, Appendix C. Data sets of 117 winter-season and 55 summer-season icing events have been statistically analysed. As defined above, the data sets include 11 winter and five summer large droplet icing encounters. Icing events included ‘sandpaper’ icing from short-duration ‘large’ droplets, and a singular ridge formation icing event in ‘large’ droplet. The frequency of ‘large’ droplet icing events amounted to 1 in 20 flight hours in winter and 1 in 35 flight hours in summer. These figures reflect ‘large’ droplet icing encounter probabilities perhaps substantially greater than previously considered. The ‘large’ droplet events were quite localised, mean scale-size being about 6nm.

scholarly journals Identification of the Aerosol Types over Athens, Greece: The Influence of Air-Mass Transport

2010 ◽  
Vol 2010 ◽  
pp. 1-15 ◽  
Author(s):  
D. G. Kaskaoutis ◽  
P. G. Kosmopoulos ◽  
H. D. Kambezidis ◽  
P. T. Nastos
Keyword(s):  
Winter Season ◽  
Saharan Dust ◽  
Dust Particles ◽  
Hysplit Model ◽  
Air Mass ◽  
Back Trajectories ◽  
Air Masses ◽  
Local Pollution ◽  
Coarse Mode ◽  
Aerosol Types

Aerosol optical depth at 550 nm () and fine-mode (FM) fraction data from Terra-MODIS were obtained over the Greater Athens Area covering the period February 2000–December 2005. Based on both and FM values three main aerosol types have been discriminated corresponding to urban/industrial aerosols, clean maritime conditions, and coarse-mode, probably desert dust, particles. Five main sectors were identified for the classification of the air-mass trajectories, which were further used in the analysis of the ( and FM data for the three aerosol types). The HYSPLIT model was used to compute back trajectories at three altitudes to investigate the relation between -FM and wind sector depending on the altitude. The accumulation of local pollution is favored in spring and corresponds to air masses at lower altitudes originating from Eastern Europe and the Balkan. Clean maritime conditions are rare over Athens, limited in the winter season and associated with air masses from the Western or Northwestern sector. The coarse-mode particles origin seems to be more complicated proportionally to the season. Thus, in summer the Northern sector dominates, while in the other seasons, and especially in spring, the air masses belong to the Southern sector enriched with Saharan dust aerosols.

A four-year record of the meteorological parameters, radiative and turbulent energy fluxes at the edge of the East Antarctic Ice Sheet, close to Schirmacher Oasis

2013 ◽  
Vol 26 (1) ◽  
pp. 93-103 ◽  
Author(s):  
H.S. Gusain ◽  
V.D. Mishra ◽  
M.K. Arora
Keyword(s):  
Heat Flux ◽  
Heat Source ◽  
Air Temperature ◽  
Meteorological Parameters ◽  
Ice Sheet ◽  
Turbulent Energy ◽  
Energy Fluxes ◽  
Glacier Surface ◽  
Katabatic Winds ◽  
Schirmacher Oasis

AbstractSurface energy fluxes of the ice sheet close to oases (ice-free land regions) are crucial in the case of retreating ice sheet and growing oasis areas. This study presents a four-year record of the meteorological parameters, radiative and turbulent energy fluxes at the edge of the Antarctic ice sheet, close to Schirmacher Oasis in Dronning Maud Land, East Antarctica from March 2007–February 2011. The energy fluxes were analysed for summer season, winter season and transition periods. High katabatic winds were observed during winter (seasonal mean 9.3 m s-1) as compared to other seasons. A high correlation (r2 = 0.89) was observed between the glacier surface temperature and air temperature, and regression relations were obtained for summer, winter and transition periods. The net radiative flux was the main heat source to the glacier during summer (46.8 W m-2) and heat sink during winter (-42.2 W m-2). Sensible heat flux (annual mean 32 W m-2) was the heat source and latent heat flux (annual mean -61 W m-2) was the heat sink to the glacier surface, averaged over all seasons. Comparison with other coastal or dry valley locations in Antarctica show that low humidity (50%), high katabatic winds (8.3 m s-1) and mild surface (-11.4°C) and air temperature (-10.2°C) contribute to high latent heat flux at the present study location.

scholarly journals Heavy Metals in PM10 Aerosols Over an Urban Industrial City

2019 ◽  
Vol 9 (1) ◽  
pp. 1402-1408
Keyword(s):  
Heavy Metal ◽  
Anthropogenic Activities ◽  
Winter Season ◽  
Principal Component ◽  
Heavy Metal Concentration ◽  
Back Trajectory ◽  
Air Masses ◽  
Back Trajectory Analysis ◽  
Source Correlation ◽  
Heavy Metal Determination

PM10 aerosols were monitored and analyzed for heavy metal concentration at Raipur city Chhattisgarh, India for possible source identification of pollutants. Sampling of PM10 aerosols was carried out by using respirable dust sampler during the year 2016. Daily PM10 average concentrations varied between 122.033 and 197.854 µg/m3, 91.350 and 133.950 µg/m3 and 112.770 and 480.170 µg/m3 in summer, monsoon and winter respectively. Chemical analysis of PM10 samples was carried out for heavy metal determination. Heavy metal (Fe, Mn, Ni and Pb) were analyzed with the help of atomic absorption spectroscopy (AAS) and found in the range of 2.713-36.862, 0.131-9.129. 0.880-4.195 and 0.015-0.321 µg/m3 for Fe, Mn, Pb and Ni respectively. PM10 concentrations shows distinct seasonal variation being twice in winter season than in summer; winter (mean: 241.820 ± 33.912 µg/m3) > summer (mean: 159.512 ± 14.360 µg/m3) > monsoon (mean: 107.480 ± 9.213 µg/m3). The concentration of heavy metal was different in all the seasons depending on their sources. Identification of possible sources was done by principal component analysis (PCA) illustrating industrial activities, soil (crustal) dust and biomass burning as the major sources in the region. The back trajectory analysis of the air masses depicts that the local anthropogenic activities affect the concentration of pollutants at the source. Correlation analysis between the heavy metal concentrations agreed the results obtained by PCA. The work helped in observing the seasonal trend of particulate matter concentrations and in identification of major sources of air pollution in the city.

scholarly journals Identification of PM10 air pollution origins at a rural background site

2018 ◽  
Vol 28 ◽  
pp. 01031 ◽  
Author(s):  
Magdalena Reizer ◽  
José A. G. Orza
Keyword(s):  
Air Pollution ◽  
Cluster Analysis ◽  
Hysplit Model ◽  
Back Trajectories ◽  
Air Masses ◽  
Rural Background ◽  
Central Eastern Europe ◽  
Background Site ◽  
North Eastern ◽  
Slow Moving

Trajectory cluster analysis and concentration weighted trajectory (CWT) approach have been applied to investigate the origins of PM10 air pollution recorded at a rural background site in North-eastern Poland (Diabla Góra). Air mass back-trajectories used in this study have been computed with the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model for a 10-year period of 2006–2015. A cluster analysis grouped back-trajectories into 7 clusters. Most of the trajectories correspond to fast and moderately moving westerly and northerly flows (45% and 25% of the cases, respectively). However, significantly higher PM10 concentrations were observed for slow moving easterly (11%) and southerly (20%) air masses. The CWT analysis shows that high PM10 levels are observed at Diabla Góra site when air masses are originated and passed over the heavily industrialized areas in Central-Eastern Europe located to the south and south-east of the site.

scholarly journals EV Overnight Charging Strategy in Residential Sector: Case of Winter Season in Quebec

Vehicles ◽  
2021 ◽  
Vol 3 (3) ◽  
pp. 557-577
Author(s):  
Alben Cardenas ◽  
Cristina Guzman ◽  
Wilmar Martinez
Keyword(s):  
Combustion Engine ◽  
Rebound Effect ◽  
Winter Season ◽  
Leading Edge ◽  
Load Shifting ◽  
High Penetration ◽  
Grid Load ◽  
Residential Demand ◽  
Ev Charging ◽  
Charging Strategy

Electric Vehicle (EV) technologies offer a leading-edge solution for clean transportation and have evolved substantially in recent years. The growing market and policies of governments predict EV massive penetration shortly; however, their large deployment faces some resistances such as the high prices compared to Internal Combustion Engine (ICE) cars, the required infrastructure, the liability for novelty and standardisation. During winter periods of cold countries, since the use of heating systems increases, the peak power may produce stress to the grid. This fact, combined with EVs high penetration, during charging periods inside of high consumption hours might overload the network, becoming a threat to its stability. This article presents a framework to evaluate load shifting strategies to reschedule the EV charging to lower grid load periods. The undesirable “rebound” effect of load shifting strategies is confirmed, leading us to our EV local overnight charging strategy (EV-ONCS). Our strategy combines the forecast of residential demand using probabilistic distribution from historical consumption, prediction of the EV expected availability to charge and the charging strategy itself. EV-ONCS avoids demand rebound of classic methods and allows a peak-to-average ratio reduction demonstrating the relief for the grid with very low implementation cost.

scholarly journals Atmospheric Biodetection Part I: Study of Airborne Bacterial Concentrations from January 2018 to May 2020 at Saclay, France

2020 ◽  
Vol 17 (17) ◽  
pp. 6292
Author(s):  
Roland Sarda-Estève ◽  
Dominique Baisnée ◽  
Benjamin Guinot ◽  
Gediminas Mainelis ◽  
John Sodeau ◽  
...  
Keyword(s):  
Urban Areas ◽  
Winter Season ◽  
Potential Health ◽  
Air Masses ◽  
Rapid Changes ◽  
Clean Air ◽  
And Shifts ◽  
Atmospheric Concentrations ◽  
Pollution Events ◽  
Bacterial Concentrations

Background: The monitoring of bioaerosol concentrations in the air is a relevant endeavor due to potential health risks associated with exposure to such particles and in the understanding of their role in climate. In this context, the atmospheric concentrations of bacteria were measured from January 2018 to May 2020 at Saclay, France. The aim of the study was to understand the seasonality, the daily variability, and to identify the geographical origin of airborne bacteria. Methods: 880 samples were collected daily on polycarbonate filters, extracted with purified water, and analyzed using the cultivable method and flow cytometry. A source receptor model was used to identify the origin of bacteria. Results: A tri-modal seasonality was identified with the highest concentrations early in spring and over the summer season with the lowest during the winter season. Extreme changes occurred daily due to rapid changes in meteorological conditions and shifts from clean air masses to polluted ones. Conclusion: Our work points toward bacterial concentrations originating from specific seasonal-geographical ecosystems. During pollution events, bacteria appear to rise from dense urban areas or are transported long distances from their sources. This key finding should drive future actions to better control the dispersion of potential pathogens in the air, like persistent microorganisms originating from contaminated areas.

scholarly journals Chemistry of snow deposited during the summer monsoon and in the winter season at Baishui glacier No. 1, Yulong mountain, China

2009 ◽  
Vol 55 (190) ◽  
pp. 221-228 ◽  
Author(s):  
Zongxing Li ◽  
Yuanqing He ◽  
Honxi Pang ◽  
Wenxiong Jia ◽  
Xianhong He ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Ionic Composition ◽  
Winter Season ◽  
Southwest Monsoon ◽  
Crustal Material ◽  
Marine Aerosols ◽  
Winter Climate ◽  
Air Masses ◽  
Yulong Mountain ◽  
Continental Origin

AbstractThe glaciers on Yulong mountain (5596 m a.s.l.), China, are the southernmost in mainland Eurasia. The largest is Baishui glacier No. 1. Up to 90% of the annual precipitation there falls in summer, when warm moisture-rich air masses associated with the southwest monsoon reach the area from the Indian Ocean. The winter climate is influenced by air masses with a continental origin and by the southern branch of the westerlies. The snow that accumulates on Baishui glacier No. 1 includes marine aerosols associated with the summer monsoon, and dust brought in winter from central/west Asia, Africa or the Thar Desert area. Studies in May 2006 at two sites, one in the accumulation area (4900 m) and one in the ablation area (4750 m), revealed differences between the ionic composition of the snow that had accumulated in the 2005/06 winter and that of the snow which had been deposited during the preceding summer monsoon. Differences in the chemistry of the summer-accumulated snow at the two sites probably reflected local differences in ablation and elution rates, rather than differences in ion supplies. Differences in the chemistry of the winter-accumulated snow may reflect the influence of up-valley winds, which bring more crustal material to the lower site.

scholarly journals The role of large-scale dynamics in an exceptional sequence of severe thunderstorms in Europe May/June 2018

2020 ◽  
Author(s):  
Susanna Mohr ◽  
Jannik Wilhelm ◽  
Jan Wandel ◽  
Michael Kunz ◽  
Raphael Portmann ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Central Europe ◽  
Large Scale ◽  
Single Cells ◽  
Low Pressure ◽  
Flash Floods ◽  
Local Scale ◽  
Air Masses ◽  
Blocking Anticyclone ◽  
Severe Thunderstorms

Abstract. Over three weeks in May and June 2018, an exceptionally large number of thunderstorms hit vast parts of western and central Europe, causing precipitation of up to 80 mm and several flash floods. During this time, the large-scale atmospheric circulation, which was characterized by a blocking situation over northern Europe, influenced atmospheric conditions relevant for thunderstorm development. Initially, the southwesterly flow on the western flank of the blocking anticyclone induced the advection of warm, moist, and unstably stratified air masses. Due to a low-pressure gradient associated with the blocking anticyclone, these air masses were trapped in western and central Europe, remained almost stationary and prevented a significant air mass exchange. In addition, the low-pressure gradient led to weak flow conditions in the mid-troposphere and thus to low vertical wind shear that prevented thunderstorms from developing into severe organized systems. Most of the storms formed as local-scale, relatively slow-moving single cells. However, due to the related weak propagation speed, several thunderstorms were able to produce torrential heavy rain that affected local-scale areas and triggered several flash floods. Atmospheric blocking also increased the upper-level cut-off low frequency on its upstream regions, which was up to 10 times higher than the climatological mean. Together with filaments of positive potential vorticity (PV), the cut-offs served as trigger mechanisms for a majority of the thunderstorms. For the 22-day study period, we found that more than 50 % of lightning strikes can be linked to a nearby cut-off low or PV filament. The exceptional persistence of low stability combined with weak wind speed in the mid-troposphere over three weeks has not been observed during the past 30 years.

scholarly journals The Effect of Mesoscale Heterogeneity on the Genesis and Structure of Mesovortices within Quasi-Linear Convective Systems

2008 ◽  
Vol 136 (11) ◽  
pp. 4220-4241 ◽  
Author(s):  
Dustan M. Wheatley ◽  
Robert J. Trapp
Keyword(s):  
Numerical Simulations ◽  
Convective Available Potential Energy ◽  
Vertical Wind Shear ◽  
Leading Edge ◽  
Real Data ◽  
Air Masses ◽  
Low Level ◽  
Convective Systems ◽  
Boundary Interaction ◽  
Outflow Boundary

Abstract This study examines the structure and evolution of quasi-linear convective systems (QLCSs) within complex mesoscale environments. Convective outflows and other mesoscale features appear to affect the rotational characteristics and associated dynamics of these systems. Thus, real-data numerical simulations of two QLCS events have been performed to (i) identify and characterize the various ambient mesoscale features that modify the structure and evolution of simulated QLCSs; and then to (ii) determine the nature of interaction of such features with the systems, with an emphasis on the genesis and evolution of low-level mesovortices. Significant low-level mesovortices develop in both simulated QLCSs as a consequence of mechanisms internal to the system—consistent with idealized numerical simulations of mesovortex-bearing QLCSs—and not as an effect of system interaction with external heterogeneity. However, meso-γ-scale (order of 10 km) heterogeneity in the form of a convective outflow boundary is sufficient to affect mesovortex strength, as air parcels populating the vortex region encounter enhanced convergence at the point of QLCS–boundary interaction. Moreover, meso-β-scale (order of 100 km) heterogeneity in the form of interacting air masses provides for along-line variations in the distributions of low- to midlevel vertical wind shear and convective available potential energy. The subsequent impact on updraft strength/tilt has implications on the vortex stretching experienced by leading-edge mesovortices.

Sign in / Sign up

Export Citation Format

Share Document