scholarly journals Astroclimatic Conditions at the Hoa Lac and Nha Trang Astronomical Observatories

Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1680
Author(s):  
Artem Y. Shikhovtsev ◽  
Pavel G. Kovadlo ◽  
Evgeniy A. Kopylov ◽  
Mansur A. Ibrahimov ◽  
Huy Le Xuan
Keyword(s):  
Wind Speed ◽  
Air Temperature ◽  
Probability Distributions ◽  
Low Frequency ◽  
Wind Speeds ◽  
Wide Range ◽  
Hourly Data ◽  
First Results ◽  
Weak Winds ◽  
High Level

The paper presents the first results of astroclimatic studies at the sites of the Hoa Lac and Nha Trang astronomical observatories. Our study employs Era-5 data covering a 10-yr time period (2011–2020). An analysis of the main astroclimatic characteristic, namely, the wind speed in the upper layers of the atmosphere, was performed. We calculated space distributions of the wind speed averaged in the height bin from 100 to 200 hPa. Using hourly data on pressure levels we analyzed probability distributions of the wind speed at high-level maxima at the sites of the observatories. At the Nha Trang observatory the period with a potentially high astroclimatic conditions falls on the spring when high recurrence of weak winds is observed. At the Hoa Lac observatory the best conditions are observed in the summer and the autumn. In this period, the median wind speeds are low. Additionally, we calculated spectra of the air temperature using the Fast Fourier Transform. We analyzed the deformations of the spectra with heights in a wide range of scales. At the site of the Nha Trang Astronomical Observatory, the amplitude of daily air temperature variations in the surface layer is approximately 1.5–2.5 times smaller compared to the Hoa Lac Observatory. We showed that the low-frequency maximum in the spectra is pronounced only in the lower layers of the atmosphere.

On the wind resource in Algeria: Probability distributions evaluation

2020 ◽  
pp. 095765092097588
Author(s):  
Houdayfa Ounis ◽  
Nawel Aries
Keyword(s):  
Wind Speed ◽  
Probability Distribution ◽  
Probability Distributions ◽  
Resource Assessment ◽  
Descriptive Statistics ◽  
The Other ◽  
Wind Speeds ◽  
Wind Resource Assessment ◽  
The Mean ◽  
Wind Resource

The present study aims to present a contribution to the wind resource assessment in Algeria using ERA-Interim reanalysis. Firstly, the ERA-Interim reanalysis 10 m wind speed data are considered for the elaboration of the mean annual 10 m wind speed map for a period starting from 01-01-2000 to 31-12-2017. Moreover, the present study intends to highlight the importance of the descriptive statistics other than the mean in wind resource assessment. On the other hand, this study aims also to select the proper probability distribution for the wind resource assessment in Algeria. Therefore, nine probability distributions were considered, namely: Weibull, Gamma, Inverse Gaussian, Log Normal, Gumbel, Generalized Extreme Value (GEV), Nakagami, Generalized Logistic and Pearson III. Furthermore, in combination with the distribution, three parameter estimation methods were considered, namely, Method of Moment, Maximum Likelihood Method and L-Moment Method. The study showed that Algeria has several wind behaviours due to the diversified topographic, geographic and climatic properties. Moreover, the annual mean 10 m wind speed map showed that the wind speed varies from 2.3 to 5.3 m/s, where 73% of the wind speeds are above 3 m/s. The map also showed that the Algerian Sahara is windiest region, while, the northern fringe envelopes the lowest wind speeds. In addition, it has been shown that the study of the mean wind speeds for the evaluation of the wind potential alone is not enough, and other descriptive statistics must be considered. On the other hand, among the nine considered distribution, it appears that the GEV is the most appropriate probability distribution. Whereas, the Weibull distribution showed its performance only in regions with high wind speeds, which, implies that this probability distribution should not be generalized in the study of the wind speed in Algeria.

Estimation of Wind Vector Profile Using a Hexarotor Unmanned Aerial Vehicle and Its Application to Meteorological Observation up to 1000 m above Surface

2018 ◽  
Vol 35 (8) ◽  
pp. 1621-1631 ◽  
Author(s):  
Tomoya Shimura ◽  
Minoru Inoue ◽  
Hirofumi Tsujimoto ◽  
Kansuke Sasaki ◽  
Masato Iguchi
Keyword(s):  
Wind Speed ◽  
Profile Measurement ◽  
Wind Vector ◽  
Doppler Lidar ◽  
Wind Speeds ◽  
Wide Range ◽  
Lidar Measurements ◽  
Ultrasonic Anemometer ◽  
Aerial Vehicle ◽  
Meteorological Observations

AbstractSmall unmanned aerial vehicles (UAVs), also known as drones, have recently become promising tools in various fields. We investigated the feasibility of wind vector profile measurement using an ultrasonic anemometer installed on a 1-m-wide hexarotor UAV. Wind vectors measured by the UAV were compared to observations by a 55-m-high meteorological tower, over a wide range of wind speed conditions up to 11 m s−1, which is a higher wind speed range than those used in previous studies. The wind speeds and directions measured by the UAV and the tower were in good agreement, with a root-mean-square error of 0.6 m s−1 and 12° for wind speed and direction, respectively. The developed method was applied to field meteorological observations near a volcano, and the wind vector profiles, along with temperature and humidity, were measured by the UAV for up to an altitude of 1000 m, which is a higher altitude range than those used in previous studies. The wind vector profile measured by the UAV was compared with Doppler lidar measurements (collected several kilometers away from the UAV measurements) and was found to be qualitatively similar to that captured by the Doppler lidar, and it adequately represented the features of the atmospheric boundary layer. The feasibility of wind profile measurement up to 1000 m by a small rotor-based UAV was clarified over a wide range of wind speed conditions.

scholarly journals The contribution of snowdrift sublimation to the surface mass balance of Antarctica

1998 ◽  
Vol 27 ◽  
pp. 251-259 ◽  
Author(s):  
Richard Bintanja
Keyword(s):  
Wind Speed ◽  
Mass Balance ◽  
Surface Mass Balance ◽  
Vertical Profiles ◽  
Sublimation Rate ◽  
Model Calculations ◽  
Surface Mass ◽  
Wind Speeds ◽  
Hourly Data ◽  
Sublimation Rates

This paper presents model calculations of snowdrift sublimation rates for year-round automatic weather station (AWS) data in Terre Adélie, Antarctica. The model calculates vertical profiles of wind speed, temperature, humidity and suspended-snow particles in the atmospheric surface layer, and takes into account the buoyancy effects induced by the stably stratified suspended-snow profile by means of an appropriate Richardson number. The model is able to simulate accurately vertical profiles of sublimation rate derived from direct measurements. The model is used to parameterise snowdrift-sublimation rates in terms of wind speed and air temperature. This parameterisation is then used to calculate snowdrift-sublimation rates from 3 hourly data of six AWSs along a transect from Dumont d'Urville to South Pole during one year. Results show that sublimation of suspended snow is negligible in the interior of Antarctica where wind speeds and temperatures are low, whereas near the windy and relatively warm coast its contribution is significant (up to 17cmw.e. a−1). Snowdrift-sublimation rates are highest during summer, when temperatures are highest, in spite of the fact that wind speeds are not as high as in winter. It is concluded that snowdrift sublimation is one of the major terms in the surface mass balance of Antarctica, in particular in the coastal regions.

scholarly journals The effects of meteorological parameters and diffusive barrier reuse on the sampling rate of a passive air sampler for gaseous mercury

2017 ◽  
Author(s):  
David S. McLagan ◽  
Carl P. J. Mitchell ◽  
Haiyong Huang ◽  
Batual Abdul Hussain ◽  
Ying Duan Lei ◽  
...  
Keyword(s):  
Wind Speed ◽  
Meteorological Parameters ◽  
Sampling Rate ◽  
Effect Of Temperature ◽  
Wind Speeds ◽  
Passive Air Sampler ◽  
Molecular Diffusivity ◽  
Air Sampler ◽  
Gaseous Mercury ◽  
High Level

Abstract. Passive air sampling of gaseous mercury (Hg) requires a high level of accuracy to discriminate small differences in atmospheric concentrations. Meteorological parameters have the potential to decrease this accuracy by impacting the sampling rate (SR), i.e., the volume of air that is effectively stripped of gaseous mercury per unit of time. We measured the SR of a recently calibrated passive air sampler for gaseous Hg in the laboratory under varying wind speeds (wind-still – 6 m s−1), temperatures (−15–35 °C), and relative humidities (44–80 %). While relative humidity has no impact on SR, SR increases slightly with both wind speed (0.003 m3 day−1 increase in SR or 2.5 % of the previously calibrated SR for every m s−1 increase for wind speeds > 1 m s−1, typical of outdoor deployments) and temperature (0.001 m3 day−1 increase in SR or 0.7 % for every 1 °C increase). The temperature dependence can be fully explained by the effect of temperature on the molecular diffusivity of gaseous mercury in air. Although these effects are relatively small, accuracy can be improved by adjusting SRs using measured or estimated temperature and wind speed data at or near sampling sites. We also assessed the possibility of reusing Radiello® diffusive barriers previously used in the passive air samplers. The mean rate of gaseous Hg uptake was not significantly different between new and previously used diffusive barriers in both lab and outdoor deployments, irrespective of the applied cleaning procedure. No memory effect from Radiellos® previously deployed in a high Hg atmosphere was observed. However, a loss in replicate precision for the dirtiest Radiellos® in the indoor experiment suggests that cleaning is advisable prior to reuse.

scholarly journals THE EFFECT OF OPENING TYPE ON THERMAL CONVENIENCE OF THE OLD AND NEW BUILDING CLASSROOM

2019 ◽  
Vol 24 (2) ◽  
pp. 75-87
Author(s):  
Ali Anton Senoaji ◽  
Arif Kusumawanto ◽  
Sentagi Sesotya Utami
Keyword(s):  
Wind Speed ◽  
Air Temperature ◽  
Mean Squared Error ◽  
Comparative Method ◽  
Field Measurements ◽  
Root Mean Squared Error ◽  
Wind Speeds ◽  
Squared Error ◽  
Simulation Results ◽  
New Buildings

This study was aimed at analyzing the effect of opening type on the thermal convenience of classrooms in old and new buildings at SMK Negeri 3 Yogyakarta. This study used a qualitative comparative method and the simulation of IES VE 2018. The field air measurement is carried out at 10 measurement points and 5 measurement points in each class, with a height of 1.5 m. Field measurements were carried out in March 2019, at 06.30-16.30 WIB. The parameters used in the study were air temperature, humidity and wind speed. Air temperature and humidity were measured using a Thermo hygrometer. Wind speed was measured using an anemometer. The data collection method is carried out by observation and measurement. Root Mean Squared Error (RMSE) was used to validate the data. The results show the best thermal convenience of the classroom was obtained during the simulation using the type of Windows Awning, with a full aperture area. Simulation results show a comfortable distribution of airflow in the classroom at wind speeds above 0.15-0.28 m/sec, Temperature 25.07-27.10oC.PENGARUH TIPE BUKAAN TERHADAP KENYAMANAN TERMAL RUANG KELAS BANGUNAN LAMA DAN BARU Tujuan dari penelitian yaitu menganalisis pengaruh bukaan terhadap kenyamanan termal ruang kelas pada bangunan lama dan baru, di SMK Negeri 3 Yogyakarta. Penelitian ini menggunakan metode komparatif kualitatif yaitu dan hasil simulasi IES VE 2018. Pengukuran udara luar dilakukan pada 10 titik pengukuran dan sebanyak 5 titik pengukuran disetiap kelasnya, dengan ketinggian 1,5 m. Pengukuran lapangan dilakukan pada bulan Maret tahun 2019, waktu 06.30-16.30 WIB. Parameter yang digunakan dalam penelitian yaitu temperatur udara, kelembaban dan kecepatan angin. Temperatur udara dan kelembaban diukur dengan menggunakan alat thermo hygrometer. Kecepatan angin diukur dengan menggunakan alat anemometer. Metode pengumpulan data dilakukan dengan metode pengamatan dan pengukuran. Validasi data menggunakan Root Mean Squared Error (RMSE). Hasil penelitian menunjukkan kenyamanan termal ruang kelas terbaik diperoleh pada saat simulasi menggunakan tipe bukaan ke atas atau Awning Windows, dengan area bukaan penuh. Hasil simulasi menunjukkan distribusi aliran udara yang nyaman di dalam ruang kelas pada kecepatan angin di atas 0,15-0,28 m/det, Temperatur 25,07 -27,10o C. 

scholarly journals Estimation of bubble-mediated air–sea gas exchange from concurrent DMS and CO<sub>2</sub> transfer velocities at intermediate–high wind speeds

2017 ◽  
Vol 17 (14) ◽  
pp. 9019-9033 ◽  
Author(s):  
Thomas G. Bell ◽  
Sebastian Landwehr ◽  
Scott D. Miller ◽  
Warren J. de Bruyn ◽  
Adrian H. Callaghan ◽  
...  
Keyword(s):  
Wind Speed ◽  
Gas Exchange ◽  
North Atlantic ◽  
Gas Transfer ◽  
Data Set ◽  
Wind Speeds ◽  
Wide Range ◽  
Carbon Dioxide Co2 ◽  
The Impact

Abstract. Simultaneous air–sea fluxes and concentration differences of dimethylsulfide (DMS) and carbon dioxide (CO2) were measured during a summertime North Atlantic cruise in 2011. This data set reveals significant differences between the gas transfer velocities of these two gases (Δkw) over a range of wind speeds up to 21 m s−1. These differences occur at and above the approximate wind speed threshold when waves begin breaking. Whitecap fraction (a proxy for bubbles) was also measured and has a positive relationship with Δkw, consistent with enhanced bubble-mediated transfer of the less soluble CO2 relative to that of the more soluble DMS. However, the correlation of Δkw with whitecap fraction is no stronger than with wind speed. Models used to estimate bubble-mediated transfer from in situ whitecap fraction underpredict the observations, particularly at intermediate wind speeds. Examining the differences between gas transfer velocities of gases with different solubilities is a useful way to detect the impact of bubble-mediated exchange. More simultaneous gas transfer measurements of different solubility gases across a wide range of oceanic conditions are needed to understand the factors controlling the magnitude and scaling of bubble-mediated gas exchange.

scholarly journals Cornice dynamics and meteorological control at Gruvefjellet, Central Svalbard

2012 ◽  
Vol 6 (1) ◽  
pp. 157-171 ◽  
Author(s):  
S. Vogel ◽  
M. Eckerstorfer ◽  
H. H. Christiansen
Keyword(s):  
Air Temperature ◽  
Meteorological Factors ◽  
Meteorological Data ◽  
Crack Opening ◽  
Time Lapse ◽  
Storm Events ◽  
Winter Climate ◽  
Wind Speeds ◽  
Prevailing Wind Direction ◽  
Wide Range

Abstract. Cornice fall avalanches endanger life and infrastructure in Nybyen, a part of Svalbard's main settlement Longyearbyen, located at 78° N in the High Arctic. Thus, cornice dynamics – accretion, cracking and eventual failure – and their controlling meteorological factors were studied along the ridgeline of the Gruvefjellet plateau mountain above Nybyen in the period 2008–2010. Using two automatic time-lapse cameras and hourly meteorological data in combination with intensive field observations on the Gruvefjellet plateau, cornice process dynamics were investigated in larger detail than previously possible. Cornice accretion starts directly following the first snowfall in late September and October, and proceeds throughout the entire snow season under a wide range of air temperature conditions that the maritime winter climate of Svalbard provides. Cornice accretion is particularly controlled by distinct storm events, with a prevailing wind direction perpendicular to the ridge line and average wind speeds from 12 m s−1. Particularly high wind speeds in excess of 30 m s−1 towards the plateau ridgeline lead to cornice scouring and reduce the cornice mass both vertically and horizontally. Induced by pronounced air temperature fluctuations which might reach above freezing and lead to midwinter rainfall events, tension cracks develop between the cornice mass and the plateau. Our measurements indicate a linear crack opening due to snow creep and tilt of the cornice around a pivot point. Four to five weeks elapsed between the first observations of a cornice crack until cornice failure. Throughout the two snow seasons studied, 180 cornice failures were recorded, of which 70 failures were categorized as distinctive cornice fall avalanches. A clear temporal pattern with the majority of cornice failures in June was found. Thus only daily air temperature could determine avalanche from non-avalanche days. Seven large cornice fall avalanches reached the avalanche fans on which the Nybyen settlement is located. The size of the avalanches was primarily determined by the size of the cornice that detached. The improved process understanding of the cornice dynamics provides a first step towards a better predictability of this natural hazard, but also highlights that any type of warning based on meteorological factors is not an adequate measure to ensure safety of the housing at risk.

scholarly journals Cornice dynamics and meteorological control at Gruvefjellet, Central Svalbard

2011 ◽  
Vol 5 (4) ◽  
pp. 2279-2318
Author(s):  
S. Vogel ◽  
M. Eckerstorfer ◽  
H. H. Christiansen
Keyword(s):  
Air Temperature ◽  
Meteorological Data ◽  
Crack Opening ◽  
Time Lapse ◽  
High Arctic ◽  
Storm Events ◽  
Winter Climate ◽  
Wind Speeds ◽  
Prevailing Wind Direction ◽  
Wide Range

Abstract. Cornice fall avalanches endanger life and infrastructure in Nybyen, a part of Svalbard's main settlement Longyearbyen, located at 78° N in the High Arctic. Thus, cornice dynamics – accretion, cracking and eventual failure – and their controlling meteorological factors were studied along the ridgeline of the Gruvefjellet plateau mountain above Nybyen in the period 2008–2010. Using two automatic time-lapse cameras and hourly meteorological data in combination with intensive field observations on the Gruvefjellet plateau, cornice process dynamics were investigated for larger detail than previously possible. Cornice accretion starts directly following the first snowfall in late September and October, and proceeds throughout the entire snow season under a wide range of air temperature conditions that the maritime winter climate of Svalbard provides. Cornice accretion is particularly controlled by distinct storm events, with a prevailing wind direction perpendicular to the ridge line and average wind speeds from 12 m s−1. Particularly high wind speeds in excess of 30 m s−1 towards the plateau ridgeline lead to cornice scouring and reduce the cornice mass both vertically and horizontally. Induced by pronounced air temperature fluctuations, tension cracks develop between the cornice mass and the plateau. Our measurements indicate a linear crack opening due to snow creep and tilt of the cornice around a pivot point. Four to five weeks elapsed between the first observations of a cornice crack until cornice failure. Throughout the two snow seasons studied, 180 cornice failures were recorded, of which 70 failures were categorized as distinctive cornice fall avalanches. A clear temporal pattern with the majority of cornice failures in June was found. Thus only daily air temperature could determine avalanche from non-avalanche days. Seven large cornice fall avalanches reached the avalanche fans on which the Nybyen settlement is located. The size of the avalanches was primarily determined by the size of the cornice that detached. The improved understanding of the cornice dynamics process provides a first step towards a better predictability of this natural hazard.

Thermodynamic Evaluation of a Small Wind Turbine

2014 ◽  
Author(s):  
Mohamed Gadalla ◽  
Sayem Zafar ◽  
Saad Ahmed
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Operating Conditions ◽  
Thermodynamic Evaluation ◽  
Ambient Conditions ◽  
Wind Speeds ◽  
Small Wind Turbine ◽  
Wide Range ◽  
Mechanical Power Output ◽  
Energy And Exergy

A small personal use wind turbine (PWT) is studied and tested for power, exergy and energy evaluation under different operating conditions. The wind turbine incorporates non-twisted blades of 1.5 m span and 0.27 m chord, using NACA 63418 airfoil. Using the earlier test results at pitch angles of 22°, 34° and 38° between the wind speeds of 4 m/s to 7 m/s, torque produced by each blade is determined. It is desired to calculate the torque as it is difficult to measure it for a small wind turbine. Using the governing equations and available computational fluid dynamics software, the total torque on each blade is determined. The resultant torque yielded the mechanical power output of the PWT. Using the available power, energy and exergy in the air flow, corresponding efficiencies are determined. To determine the changes in energy and exergy with respect to the wind speed, wind-chill factor expression is utilized. Results are collected for a wide range of wind speeds and pitch angles. Power, energy, exergy and their corresponding efficiency is evaluated to determine the optimal use pitch angle and ambient conditions. The pitch angles of 22° and 38o yielded high efficiencies although 22° produced the higher rotational speed as compared to 38°. The result suggests better performance for continuous wind speed conditions at low pitch angles — with respect to the rotating plane. For non-continuous wind conditions, higher pitch angles appeared beneficial.

scholarly journals UTCI applications in practice (methodological questions)

2021 ◽  
Vol 94 (2) ◽  
pp. 153-165
Author(s):  
Krzysztof Błażejczyk ◽  
Magdalena Kuchcik
Keyword(s):  
Wind Speed ◽  
Human Health ◽  
Air Temperature ◽  
Meteorological Data ◽  
Mean Radiant Temperature ◽  
Change Analysis ◽  
Complex Index ◽  
Wide Range ◽  
Radiant Temperature

UTCI, although it was developed with the participation of scientists from 22 countries, it has shortcomings and people using it face various obstacles. The difficulties include wide range of issues: from different availability of meteorological data in individual countries, through the kind of air temperature which should be properly used in calculations, or the need of recalculation of wind speed. However the biggest subject concern algorithms for mean radiant temperature (Mrt) calculations, different models and programs which simplify calculations of this complex index though introduce different approximations and, as a result, many false results. The paper presents also wide range of UTCI applications in urban bioclimate studies and bioclimatic mapping, climate-human health researches and biometeorological forecasts which were the primary purpose of the index creation, but also applications in tourism and recreation or even in bioclimate change analysis.

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