scholarly journals The Relationship between Air Stability and Visibility over Baghdad City

2021 ◽  
Vol 32 (2) ◽  
pp. 82
Author(s):  
Ahmed F. Hassoon ◽  
Mohammed M. Ahmed ◽  
Nadia M. Abd
Keyword(s):  
Wind Speed ◽  
Solar Radiation ◽  
Atmospheric Stability ◽  
Weather Conditions ◽  
Neutral Condition ◽  
Stability Class ◽  
Stable Conditions ◽  
Class B ◽  
Using Data ◽  
The Stability

In this study, Pasquill atmospheric stability determined at daytime for January and July 2010 fixed for Baghdad city. The classification of stability was made using data of wind speed and solar radiation. These classes were compared with atmospheric stability recorded hourly in Baghdad airport station. The results show that stability class, B and C make up the highest percentages, while class A is non-existent during winter "this" can be attributed to prevailing parameter weather and their frequencies such as temperature, wind speed, and solar radiation. The stability classes were estimated to be medium to moderate. In summer, B and A-B stability classes were more predominant than others. Visibility in January month is very high and concentrated at 8500-11500 meters and has a rate of 75%, while the bad visibility range at this month is about 7.6%. In July month the rate of clear weather conditions of visibility is about 65.8%. Atmospheric elements (temperature, relative humidity wind speed, solar radiation) are compared with visibility at specified stability class to show it’s affected on visibility. If more stable conditions existed this refers to the better extent of visibility, this means unstable conditions reduce atmospheric visibility with help of atmospheric elements. Overall, the most affected class on the visibility is neutral condition and near-neutral condition, but you may determine the location if there is near to the location of emission pollutant or aerosols, consequently, the case is different.

Assessing Peak-To-Mean Ratios of Odour Intensity in the Atmosphere near Swine Operations

Atmosphere ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 224
Author(s):  
Qiang Zhang ◽  
Xiaojing Zhou
Keyword(s):  
Atmospheric Stability ◽  
Ambient Air ◽  
Noticeable Effect ◽  
Stability Class ◽  
Odour Source ◽  
Class B ◽  
Swine Operations ◽  
Measurement Session ◽  
Averaging Time

Odour in the atmosphere is usually characterized by an intermittent time series of high peaks and periods of low (or zero) concentrations. The peak-to-mean ratio (PMR) is commonly used to estimate short-term peaks from long-term averages to assess the odour impact. The objective of this study was to quantify the peak-to-mean ratio of odour intensity (PMR_OI) in the atmosphere near swine operations. Fifteen human assessors (sniffers) were trained to use an 8 point odour intensity scale to measure odour intensity in the ambient air near two swine operations. In each measurement session, the sniffers were placed 0° (in the direction of wind), 30°, and 45° from the wind directions at 100, 500, and 1000 m from the swine operations to sniff odour in the air every 10 s for 30 min. The results showed that odour in the atmosphere was intermittent. The intermittency (% of time when odour was detected) increased with the averaging time and decreased with the distance from the odour source and the direction from the wind. The measured intermittency ranged from 13% to 85%. The PMR_OI increased with the averaging time, the distance from the source, and the direction from the wind. In the wind direction, the largest difference in PMR_OI between 1 and 30 min averaging times was 68% (2.5 vs. 4.2), which occurred at 1000 m from the odour source under stability class B. The average PMR_OI increased from 1.5 at 100 m to 3.5 at 1000 m. Atmospheric stability had a noticeable effect on PMR_OI. At 1000 m, the 30 min PMR_OI decreased from 4.2 at stability class B (unstable) to 2.4 at E (slightly stable).

scholarly journals Assessment of the unified analytical solution of the steady-state atmospheric diffusion equation for stable conditions

2014 ◽  
Vol 470 (2167) ◽  
pp. 20140021 ◽  
Author(s):  
L. C. G. Pimentel ◽  
J. S. Pérez Guerrero ◽  
A. G. Ulke ◽  
F. P. Duda ◽  
P. F. L. Heilbron Filho
Keyword(s):  
Steady State ◽  
Wind Speed ◽  
Analytical Solution ◽  
Eigenvalue Problem ◽  
Atmospheric Diffusion ◽  
Stable Conditions ◽  
Prairie Grass ◽  
The Stability ◽  
Good Agreement ◽  
Diffusion Problems

In this work, the performance of a unified formal analytical solution for the simulation of atmospheric diffusion problems under stable conditions is evaluated. The eigenquantities required by the formal analytical solution are obtained by solving numerically the associated eigenvalue problem based on a newly developed algorithm capable of being used in high orders and without missing eigenvalues. The performance of the formal analytical solution is evaluated by comparing the converged predicted results against the observed values in the stable runs of the Prairie Grass experiment as well as the simulated results available in the literature. It was found that the developed algorithm was efficient and that the convergence rate depends on the stability condition and the considered parametrizations for wind speed and turbulence. The comparisons among predicted and observed concentrations showed a good agreement and indicate that the considered dispersion formulations are appropriate to simulate dispersion under slightly to moderate atmospheric stable conditions.

scholarly journals The Role of Atmospheric Stability and Turbulence in Offshore Wind-Farm Wakes in the German Bight

2021 ◽  
Author(s):  
Andreas Platis ◽  
Marie Hundhausen ◽  
Astrid Lampert ◽  
Stefan Emeis ◽  
Jens Bange
Keyword(s):  
German Bight ◽  
Wind Farm ◽  
Atmospheric Stability ◽  
Wind Farms ◽  
Offshore Wind ◽  
Lapse Rate ◽  
Offshore Wind Farm ◽  
Near Surface ◽  
Stable Conditions ◽  
The Stability

AbstractAirborne meteorological in situ measurements as well as stationary measurements at the offshore masts FINO1 and FINO3 in the German Bight are evaluated in order to examine the hypothesis that the wake dissipation downstream of large offshore wind farms depends on atmospheric stability. A long-term study of the mast data for the years 2016 and 2017 demonstrates a clear dependence of stability on the wind direction. Stable conditions are predominantly expected during southerly winds coming from the land. The analysis of various stability and turbulence criteria shows that the lapse rate is the most robust parameter for stability classification in the German Bight, but further implies that stability depends on the measurement height. A near-surface (0 to 30 m), predominantly convective, layer is present and more stable conditions are found aloft (55 to 95 m). Combing the stability data with the airborne measurements of the offshore wind-farm wakes reveals the trend of a correlation between longer wake lengths and an increase in the initial wind-speed deficit downwind of a wind farm with stronger thermal stability. However, the stability correlation criteria with the wake length downstream of the four investigated wind farms, Godewind, Amrumbank West, Meerwind Süd/Ost, and Nordsee Ost, contain large variance. It is assumed that the observed scattering is due to the influence of the wind-farm architecture and temperature inversions around hub height. These, however, are crucial for the classification of stability and illustrate the complexity of a clear stability metric.

scholarly journals Seasonality in onshore normalized wind profiles above the surface layer

2010 ◽  
Vol 4 (1) ◽  
pp. 57-62 ◽  
Author(s):  
J. N. Nissen ◽  
S.-E. Gryning
Keyword(s):  
Surface Layer ◽  
Wind Speed ◽  
Marine Boundary Layer ◽  
Mesoscale Model ◽  
Atmospheric Stability ◽  
Relative Difference ◽  
Stability Class ◽  
Surface Stability ◽  
Wind Speeds ◽  
Seasonal Signal

Abstract. This work aims to study the seasonal difference in normalized wind speed above the surface layer as it is observed at the 160 m high mast at the coastal site Høvsøre at winds from the sea (westerly). Normalized and stability averaged wind speeds above the surface layer are observed to be 20 to 50% larger in the winter/spring seasons compared to the summer/autumn seasons at winds from west within the same atmospheric stability class. A method combining the mesoscale model, COAMPS, and observations of the surface stability of the marine boundary layer is presented. The objective of the method is to reconstruct the seasonal signal in normalized wind speed and identify the physical process behind. The method proved reasonably successful in capturing the relative difference in wind speed between seasons, indicating that the simulated physical processes are likely candidates to the observed seasonal signal in normalized wind speed.

Measuring Sub-second Wind Velocity Changes for Agricultural Drift One Meter Above the Ground

2019 ◽  
Vol 35 (5) ◽  
pp. 697-704
Author(s):  
Matthew W. Schramm ◽  
H Mark Hanna ◽  
Matt J. Darr ◽  
Steven J. Hoff ◽  
Brian L. Steward
Keyword(s):  
Wind Speed ◽  
Solar Radiation ◽  
Wind Velocity ◽  
Wind Direction ◽  
Weather Conditions ◽  
Spray Drift ◽  
Average Wind Speed ◽  
Wind Speeds ◽  
Average Wind ◽  
Velocity Changes

Abstract. Agricultural spray drift is affected by many factors including current weather conditions, topography of the surrounding area, fluid properties at the nozzle, and the height at which the spray is released. During the late spring/summer spray seasons of 2014 and 2015, wind direction, speed, and solar radiation (2014 only) were measured at 10 Hz, 1 m above the ground to investigate conditions that are typically encountered by a droplet when released from a nozzle on an agricultural sprayer. Measurements of wind velocity as the wind passed from an upwind sensor to a downwind sensor were used to evaluate what conditions wind may be most likely to have a significant direction or speed change which affects droplet trajectory. For two individual datasets in which the average wind speed was 3.6 and 1.5 m/s (8.0 and 3.4 mi/h), there exists little linear correlation of wind speed or wind direction between an upwind and downwind anemometer separated by 30.5 m (100 ft). The highest observed correlation, resulting from a 12-s lag between the upwind and downwind datasets, was 0.29 when the average wind speed was 3.6 m/s (8.0 mi/h). Correlations greater than 0.1 were only found for wind speeds exceeding 3 m/s. Using this lag time, it was observed that the wind direction 30 s into the future had a 30% chance to be different by more than 20° from current conditions. A wind speed difference of more than 1 m/s (2.2 mi/h) from current conditions [mean wind speed was 3.6 m/s (8.0 mi/h)] was observed about 50% of the time. Analyzing 36 days of the 2014 and 2015 spray season wind velocity data showed that the most variability in wind direction occurred with wind speeds below 2 m/s (4.5 mi/h). Greater wind direction variability occurred in the mid-afternoon with higher solar radiation. Keywords: Sprayers, Spray drift, Spray droplets, Turbulence, Wind effects.

scholarly journals Characteristics of the Springtime Alpine Valley Atmospheric Boundary Layer Using Self-Organizing Maps

2015 ◽  
Vol 54 (10) ◽  
pp. 2077-2085 ◽  
Author(s):  
Marwan Katurji ◽  
Bob Noonan ◽  
Peyman Zawar-Reza ◽  
Tobias Schulmann ◽  
Andrew Sturman
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Atmospheric Boundary Layer ◽  
Learning Algorithm ◽  
Potential Temperature ◽  
Atmospheric Stability ◽  
Weather Conditions ◽  
Self Organizing Maps ◽  
Alpine Valley ◽  
Self Organizing

AbstractVertical profiles of wind velocity and air temperature from a sound detection and ranging (sodar) radio acoustic sounding system (RASS)-derived dataset within an alpine valley of the New Zealand Southern Alps were analyzed. The data covered the month of September 2013, and self-organizing maps (SOM; a data-clustering approach that is based on an unsupervised machine-learning algorithm) are used to detect topological relationships between profiles. The results of the SOM were shown to reflect the physical processes within the valley boundary layer by preserving valley boundary layer dynamics and its response to wind shear. By examining the temporal evolution of ridgetop wind speed and direction and SOM node transitions, the sensitivity of the valley boundary layer to ridgetop weather conditions was highlighted. The approach of using a composite variable (wind speed and potential temperature) with SOM was successful in revealing the coupling of dynamics and atmospheric stability. The results reveal the capabilities of SOM in analyzing large datasets of atmospheric boundary layer measurements and elucidating the connectivity of ridgetop wind speeds and valley boundary layers.

scholarly journals Automated wind turbine wake characterization in complex terrain

2019 ◽  
Vol 12 (6) ◽  
pp. 3463-3484 ◽  
Author(s):  
Rebecca J. Barthelmie ◽  
Sara C. Pryor
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Atmospheric Stability ◽  
Average Height ◽  
Data Set ◽  
Wind Speeds ◽  
Stable Conditions ◽  
Low Wind Speeds ◽  
Turbine Wake ◽  
Wind Turbine Wake

Abstract. An automated wind turbine wake characterization algorithm has been developed and applied to a data set of over 19 000 scans measured by a ground-based scanning Doppler lidar at Perdigão, Portugal, over the period January to June 2017. Potential wake cases are identified by wind speed, direction and availability of a retrieved free-stream wind speed. The algorithm correctly identifies the wake centre position in 62 % of possible wake cases, with 46 % having a clear and well-defined wake centre surrounded by a coherent area of lower wind speeds while 16 % have split centres or multiple lobes where the lower wind speed volumes are no longer in coherent areas but present as two or more distinct areas or lobes. Only 5 % of cases are not detected; the remaining 33 % could not be categorized either by the algorithm or subjectively, mainly due to the complexity of the background flow. Average wake centre heights categorized by inflow wind speeds are shown to be initially lofted (to two rotor diameters, D, downstream) except when the inflow wind speeds exceed 12 ms−1. Even under low wind speeds, by 3.5 D downstream of the wind turbine, the mean wake centre position is below the initial wind turbine hub height and descends broadly following the terrain slope. However, this behaviour is strongly linked to the hour of the day and atmospheric stability. Overnight and in stable conditions, the average height of the wake centre is 10 m higher than in unstable conditions at 2 D downstream from the wind turbine and 17 m higher at 4.5 D downstream.

scholarly journals Drag Coefficient during Strong Typhoons

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Binglan Wang ◽  
Lili Song ◽  
Wenchao Chen
Keyword(s):  
Wind Speed ◽  
Drag Coefficient ◽  
Atmospheric Stability ◽  
Weakly Stable ◽  
Using Data ◽  
The Relationship

Using data from wind towers during typhoons Hagupit and Nuri, drag coefficient was estimated. The relationship between drag coefficient and atmospheric stability was examined. The results indicate that the drag coefficient decreased when atmosphere stability changed from weakly stable or unstable to neutral. Relationship between drag coefficient and wind speed was also examined, and the results indicate that the relationships between drag coefficient and wind speed were similar to other researchers’ result, but the wind thresholds were different due to different observation sites. Quantitative expressions between drag coefficient and wind speed were derived.

scholarly journals Dispersi Polutan Karbon Monoksida di Sekitar Pintu Tol Baranangsiang Bogor (Carbon monoxide Dispersion in the Vicinity of Baranangsiang Toll Gateway in Bogor)

1970 ◽  
Vol 4 (2) ◽  
pp. 27-35
Author(s):  
Yudith Vega Paramitadevi
Keyword(s):  
Carbon Monoxide ◽  
Medical Records ◽  
Atmospheric Stability ◽  
Motor Vehicles ◽  
Stability Class ◽  
The Past ◽  
Co Intoxication ◽  
Co Concentration ◽  
Class B ◽  
Heavy Burden

Over the past decade, emission from carbon monoxide (CO) has risen due to the increase of vehicles per year. Bogor as a weekend tourist tour town has a heavy burden in the terms of the volume of motor vehicles. The object of this study is Baranangsiang Bogor toll gateway, where queue of motor vehicles is often the case, and allegedly produces many pollutants CO. This study was conductes to simulate the CO concentration by the method of Finite Length Line Source (FLLS) aroung Baranangsiang Bogor toll gateway and recapitulate types of diseases associated with CO impacts on communities around the toll is in line with the pattern of increase in the volume of vehicles at 6% per years. Based on the result of measurements and simulations that were conducted on four sampling points within 20 m and 190 m from the sources pollutions on 26th August to 1st September 2014, the concentration of CO is still within the range of quality standards in accordance with Regulation No. 41 of 1999 which is 634-9189 µg/Nm3. Dispesion of pollutants CO dominantly heading Eastwards with the wind speed measurements 1.5-5.2 m/s and atmospheric stability class B. Kampung Sawah RT 02 RW 07is exposed to higher CO. Recapitulation of medical records showed that CO intoxication suspected cases of the disease are more common in Kampung Sawah housing than IPB Baranangsiang 4 Settlement.Keywords : Baranangsiang Toll Gate, Carbon Monoxide, CO Intoxication, Dispersion CO

scholarly journals Effects of Atmospheric Surface Layer Stability on Turbulent Fluxes of Heat and Water Vapor across the Water–Atmosphere Interface

2016 ◽  
Vol 17 (11) ◽  
pp. 2835-2851 ◽  
Author(s):  
Yusri Yusup ◽  
Heping Liu
Keyword(s):  
Heat Flux ◽  
Surface Layer ◽  
Wind Speed ◽  
Temperature Gradient ◽  
Atmospheric Surface Layer ◽  
Numerical Models ◽  
Atmospheric Stability ◽  
Stable Conditions ◽  
Vapor Pressure Gradient ◽  
Stability Ranges

Abstract Widely used numerical models to estimate turbulent exchange of latent heat flux (LE) and sensible heat flux H across the water–atmosphere interface are based on the bulk transfer relations linked indirectly to atmospheric stability, even though the accurate prediction of the influence of stability on fluxes is uncertain. Here eddy covariance data collected over the water surface of Ross Barnett Reservoir, Mississippi, was analyzed to study how atmospheric stability and other variables (wind speed, vapor pressure gradient, and temperature gradient) in the atmospheric surface layer (ASL) modulated LE and H variations in different stability ranges. LE and H showed right-skewed, bell-shaped distributions as the ASL stability shifted from very unstable to near neutral and then stable conditions. The results demonstrate that the maximum (minimum) LE and H did not necessarily occur under the most unstable (stable) conditions, but rather in the intermediate stability ranges. No individual variables were able to explain the dependence of LE and H variations on stability. The coupling effects of stability, wind speed, and vapor pressure gradient (temperature gradient) on LE (H) primarily caused the observed variations in LE and H in different stability ranges. These results have important implications for improving parameterization schemes to estimate fluxes over water surfaces in numerical models.

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