scholarly journals Measurements of natural airflow within a Stevenson screen

2021 ◽  
Author(s):  
Stephen David Burt
Keyword(s):  
Wind Speed ◽  
Air Temperature ◽  
Response Times ◽  
Sonic Anemometer ◽  
Climate Science ◽  
Ventilation Rate ◽  
Air Temperatures ◽  
Temperature And Humidity ◽  
Mean Wind Speed ◽  
Stevenson Screen

Abstract. Climate science depends upon accurate measurements of air temperature and humidity, the majority of which are still derived from sensors exposed within passively-ventilated louvred Stevenson-type thermometer screens. It is well-documented that, under certain circumstances, air temperatures measured within such screens can differ significantly from ‘true’ air temperatures measured by other methods, such as aspirated sensors. Passively-ventilated screens depend upon wind motion to provide ventilation within the screen, and thus airflow over the sensors contained therein. Consequently, instances of anomalous temperatures occur most often during light winds when airflow through the screen is weakest, particularly when in combination with strong or low-angle incident solar radiation. Adequate ventilation is essential for reliable and consistent measurements of both air temperature and humidity, yet very few systematic comparisons to quantify relationships between external wind speed and airflow within a thermometer screen have been made. This paper addresses that gap by summarising the results of a three month field experiment in which airflow within a UK-standard Stevenson screen was measured using a sensitive sonic anemometer, and comparisons made using simultaneous wind speed and direction records from the same site. The average in-screen ventilation rate was found to be 0.2 m s−1, well below the 1 m s−1 minimum assumed in meteorological and design standard references, and only about 7 % of the scalar mean wind speed at 10 m. The implications of low in-screen ventilation on the uncertainty of air temperature and humidity measurements from Stevenson-type thermometer screens are discussed, particularly those due to the differing response times of dry- and wet-bulb temperature sensors, and ambiguity in the value of the psychrometric coefficient.

scholarly journals Exposure-Dependent Variations in Air Temperature and Humidity on the Moraine of the Aavatsmark Glacier (Nw Spitsbergen) in the Summer Season of 2010

2012 ◽  
Vol 5 (1) ◽  
pp. 57-75
Author(s):  
Andrzej Araźny ◽  
Rajmund Przybylak
Keyword(s):  
Wind Speed ◽  
Air Temperature ◽  
Weather Conditions ◽  
Active Surface ◽  
Summer Season ◽  
Lateral Moraine ◽  
Near Surface ◽  
Mean Values ◽  
Temperature And Humidity ◽  
Surface Air Layer

Abstract The article presents results of research on the development of air temperature and relative humidity at a height of 5 cm above the active surface of the terminal lateral moraine of the Aavatsmark Glacier, relative to its exposure in the summer season of 2010. Variations in the two conditions were analysed for five measurement sites situated on northerly (SN), easterly (SE), southerly (SS) and westerly (SW) slopes, as well as on the flat top surface of the moraine (STop), in different weather conditions. The article also includes a temperature and humidity stratification in the near surface air layer (5-200 cm) above the moraine. The issues were investigated for mean values from the whole period of research, as well as for individual days demonstrating distinct degrees of cloudiness and wind speed.

scholarly journals Field intercomparison of prevailing sonic anemometers

2018 ◽  
Vol 11 (1) ◽  
pp. 249-263 ◽  
Author(s):  
Matthias Mauder ◽  
Matthias J. Zeeman
Keyword(s):  
Wind Speed ◽  
Sonic Anemometer ◽  
Three Dimensional ◽  
Buoyancy Flux ◽  
Horizontal Wind ◽  
Horizontal Wind Speed ◽  
Sonic Anemometers ◽  
Adjacent Structures ◽  
Mean Wind Speed ◽  
Field Intercomparison

Abstract. Three-dimensional sonic anemometers are the core component of eddy covariance systems, which are widely used for micrometeorological and ecological research. In order to characterize the measurement uncertainty of these instruments we present and analyse the results from a field intercomparison experiment of six commonly used sonic anemometer models from four major manufacturers. These models include Campbell CSAT3, Gill HS-50 and R3, METEK uSonic-3 Omni, R. M. Young 81000 and 81000RE. The experiment was conducted over a meadow at the TERENO/ICOS site DE-Fen in southern Germany over a period of 16 days in June of 2016 as part of the ScaleX campaign. The measurement height was 3 m for all sensors, which were separated by 9 m from each other, each on its own tripod, in order to limit contamination of the turbulence measurements by adjacent structures as much as possible. Moreover, the high-frequency data from all instruments were treated with the same post-processing algorithm. In this study, we compare the results for various turbulence statistics, which include mean horizontal wind speed, standard deviations of vertical wind velocity and sonic temperature, friction velocity, and the buoyancy flux. Quantitative measures of uncertainty, such as bias and comparability, are derived from these results. We find that biases are generally very small for all sensors and all computed variables, except for the sonic temperature measurements of the two Gill sonic anemometers (HS and R3), confirming a known transducer-temperature dependence of the sonic temperature measurement. The best overall agreement between the different instruments was found for the mean wind speed and the buoyancy flux.

INFLUENCE OF TEMPERATURE AND HUMIDITY ON THE EMERGENCE BEHAVIOUR OF ANAX JUNIUS (ODONATA: AESHNIDAE)

1973 ◽  
Vol 105 (7) ◽  
pp. 975-984 ◽  
Author(s):  
Robert Trottier
Keyword(s):  
Relative Humidity ◽  
Water Temperature ◽  
Air Temperature ◽  
Water Surface ◽  
Average Speed ◽  
Anax Junius ◽  
Air Temperatures ◽  
Stage 4 ◽  
Temperature And Humidity ◽  
Three Stages

AbstractEmergence from the water of Anax junius Drury normally occurred after sunset. The onset was affected independently by water temperature and air temperature; low water temperature and high air temperature delayed the onset of emergence. In the field, the net vrtical distance travelled above the water, before ecdysis, was positively correlated with air temperature. In the laboratory, the vertical distance travelled above the water was greatest when air and water temperatures were approximately the same. The average speed of climbing to the first resting position above the water surface was faster at high than low water temperature, but the average speed of climbing from there to the final position, where ecdysis occurred, was reduced due to the effects of air temperature and humidity. Air temperatures below 12.6 °C were found to retard ecdysis and larvae returned to the water and emerged early the following day making the final process of emergence and ecdysis diurnal instead of nocturnal. The duration of ecdysis was shorter at high than low air temperatures and only the first three stages, as arbitrarily defined, were longer at low than high relative humidity; stage 4, shortened with low relative humidity. This study shows that A. Junius, emerging from the water is affected at first by the temperature experienced when submerged, but it becomes gradually and cumulatively affected by air temperature and humidity while climbing to the ecdysial position and moulting.

THE INFLUENCE OF ENVIRONMENTAL TEMPERATURE AND HUMIDITY ON SHOCK PRODUCED BY A CLAMPING PROCEDURE

1959 ◽  
Vol 37 (2) ◽  
pp. 165-174
Author(s):  
R. E. Haist ◽  
Rebeka Moscarello ◽  
T. L. Friedlich ◽  
J. R. Hamilton
Keyword(s):  
Air Temperature ◽  
Significant Influence ◽  
Environmental Temperature ◽  
Limb Ischemia ◽  
Optimum Temperature ◽  
Standard Temperature ◽  
Air Temperatures ◽  
Temperature And Humidity ◽  
Different Temperatures ◽  
Environmental Temperatures

The influence of environmental temperature on the development of shock produced by a clamping technique in rats was studied. In experiments in which the animals were subjected to different environmental temperatures during the period of limb ischemia, the best survival was obtained with an air temperature of 15 °C. At 9.5 °C and 40 °C the rats did not survive the 10-hour clamping period. When the clamping was carried out at a standard temperature (27 °C) and the rats were then transferred to a room at different temperatures just prior to clamp release, the best survival was obtained at or near a temperature of 24 °C. The temperature in the colon of the shocked rats fell quickly in a cooler environment and rose in a warmer one. When chlorpromazine (0.35 mg/100 g rat) was given at the time of clamp removal to rats kept thereafter at 9.4 °C, 20–21 °C, 24 °C, and 30 °C, survival was significantly prolonged at air temperatures of 20–21 °C, but not at 9.4 °C, 24 °C, or 30 °C. Changes in humidity had no significant influence on survival. The experiments show that the optimum temperature during the period of ischemia is different from that for hindering the development of shock following a period of ischemia.

THE INFLUENCE OF ENVIRONMENTAL TEMPERATURE AND HUMIDITY ON SHOCK PRODUCED BY A CLAMPING PROCEDURE

1959 ◽  
Vol 37 (1) ◽  
pp. 165-174
Author(s):  
R. E. Haist ◽  
Rebeka Moscarello ◽  
T. L. Friedlich ◽  
J. R. Hamilton
Keyword(s):  
Air Temperature ◽  
Significant Influence ◽  
Environmental Temperature ◽  
Limb Ischemia ◽  
Optimum Temperature ◽  
Standard Temperature ◽  
Air Temperatures ◽  
Temperature And Humidity ◽  
Different Temperatures ◽  
Environmental Temperatures

The influence of environmental temperature on the development of shock produced by a clamping technique in rats was studied. In experiments in which the animals were subjected to different environmental temperatures during the period of limb ischemia, the best survival was obtained with an air temperature of 15 °C. At 9.5 °C and 40 °C the rats did not survive the 10-hour clamping period. When the clamping was carried out at a standard temperature (27 °C) and the rats were then transferred to a room at different temperatures just prior to clamp release, the best survival was obtained at or near a temperature of 24 °C. The temperature in the colon of the shocked rats fell quickly in a cooler environment and rose in a warmer one. When chlorpromazine (0.35 mg/100 g rat) was given at the time of clamp removal to rats kept thereafter at 9.4 °C, 20–21 °C, 24 °C, and 30 °C, survival was significantly prolonged at air temperatures of 20–21 °C, but not at 9.4 °C, 24 °C, or 30 °C. Changes in humidity had no significant influence on survival. The experiments show that the optimum temperature during the period of ischemia is different from that for hindering the development of shock following a period of ischemia.

scholarly journals Wind Measurements from Arc Scans with Doppler Wind Lidar

2015 ◽  
Vol 32 (11) ◽  
pp. 2024-2040 ◽  
Author(s):  
H. Wang ◽  
R. J. Barthelmie ◽  
A. Clifton ◽  
S. C. Pryor
Keyword(s):  
Wind Speed ◽  
Sonic Anemometer ◽  
Elevation Angle ◽  
Horizontal Wind ◽  
Horizontal Wind Speed ◽  
Energy Applications ◽  
Mean Wind Speed ◽  
Wind Measurements ◽  
Wind Lidar ◽  
Doppler Wind Lidar

AbstractDefining optimal scanning geometries for scanning lidars for wind energy applications remains an active field of research. This paper evaluates uncertainties associated with arc scan geometries and presents recommendations regarding optimal configurations in the atmospheric boundary layer. The analysis is based on arc scan data from a Doppler wind lidar with one elevation angle and seven azimuth angles spanning 30° and focuses on an estimation of 10-min mean wind speed and direction. When flow is horizontally uniform, this approach can provide accurate wind measurements required for wind resource assessments in part because of its high resampling rate. Retrieved wind velocities at a single range gate exhibit good correlation to data from a sonic anemometer on a nearby meteorological tower, and vertical profiles of horizontal wind speed, though derived from range gates located on a conical surface, match those measured by mast-mounted cup anemometers. Uncertainties in the retrieved wind velocity are related to high turbulent wind fluctuation and an inhomogeneous horizontal wind field. The radial velocity variance is found to be a robust measure of the uncertainty of the retrieved wind speed because of its relationship to turbulence properties. It is further shown that the standard error of wind speed estimates can be minimized by increasing the azimuthal range beyond 30° and using five to seven azimuth angles.

Estimating absolute densities of the bushfly, Musca vetustissima Walker (Diptera: Muscidae), using West Australian blowfly traps

1981 ◽  
Vol 71 (2) ◽  
pp. 329-337 ◽  
Author(s):  
W. G. Vogt ◽  
T. L. Woodburn ◽  
G. W. Crompton
Keyword(s):  
Wind Speed ◽  
Population Density ◽  
Air Temperature ◽  
Recovery Rate ◽  
Weather Conditions ◽  
Mean Wind Speed ◽  
Dispersal Distances ◽  
True Population

AbstractCatches of Musca vetustissima Wlk. in West Australian blowfly traps containing week-old baits were consistently greater (4·5–24·1 times higher) than in traps with fresh baits. Recovery of marked flies within 26·5h of release showed mean dispersal distances of 1·5 ± 0·7 km for males and 1·6 ± 0·6 km for females under favourable weather conditions (mean air temperature 28·8°C and mean wind speed 5·5 m/s). The recovery rate of males (1·3%) and females (1·0%) over this period indicates the feasibility of using single mark-release experiments to estimate absolute fly densities. It is shown that estimates having a 95% probability of being within ± 10% of the true population density could be achieved by the release of 39 000 marked flies.

scholarly journals Evaluation of the Flow Distortion around the Campbell Scientific CSAT3 Sonic Anemometer Relative to Incident Wind Direction

2009 ◽  
Vol 26 (3) ◽  
pp. 582-592 ◽  
Author(s):  
Harry C. Friebel ◽  
Thomas O. Herrington ◽  
Alexander Y. Benilov
Keyword(s):  
Wind Speed ◽  
Momentum Transfer ◽  
Wind Direction ◽  
High Frequency ◽  
Surf Zone ◽  
Spectral Characteristics ◽  
Sonic Anemometer ◽  
Flow Distortion ◽  
Mean Wind Speed ◽  
The Mean

Abstract In June 2002, a high-frequency air–sea momentum system was deployed in the surf zone for 3 days as part of an experiment to quantify air–sea momentum transfer when the wind and wave direction were at angles. The system obtained measurements in the nearshore via a high-resolution Campbell Scientific CSAT3 3D sonic anemometer and five high-frequency saltwater wave staffs. An advantage of the air–sea momentum system is that direct measurements of the atmospheric turbulent fluctuations can be obtained and applied to the calculation of momentum transfer at the air–sea interface. The Campbell Scientific CSAT3 sonic anemometer was postcalibrated under turbulent wind conditions to determine incident wind direction measurements influenced by the geometry of the instrument. Measurement results are compared to a pre-established benchmark, constant tow speed; and the mean wind speed, incident wind direction, and spectral density characteristics are evaluated to resolve specific instrument orientations in which the measurements are corrupted by the head and probe supports of the sonic anemometer. Calibration testing of the sonic anemometer determined that the mean wind speeds are reduced by 16% over a 40° range for incident wind angles of 160°–200° relative to the head of the anemometer. Tilting the anemometer is found to decrease mean wind speed reduction influenced by the geometry of the anemometer. Variations in the measured wind directions were found to be greater than 1° for incident wind angles between 160° and 200° for 0° and 10° of tilt. Spectral characteristics were highly repeatable for all wind angles except for incident wind angles of 180° for 0° and 10° of tilt.

scholarly journals Accounting for real meteorological conditions at the time of UAV flight mission planning

2021 ◽  
pp. 54-60
Author(s):  
P. Tkachyck ◽  
O. Kotcemyr ◽  
S. Sokolovskyi ◽  
D. Bilous
Keyword(s):  
Wind Speed ◽  
Air Temperature ◽  
Armed Forces ◽  
Meteorological Conditions ◽  
Full Spectrum ◽  
The Real ◽  
State Tests ◽  
Wind Speeds ◽  
Charge Current ◽  
Air Temperatures

The article is dedicated to the the problem of not considering the real meteorological conditions in planning the flight task of the unmanned aerial vehicle (UAV) A1-CM Furia . Unmanned aerial system(UAS) A1-CM  Furia  has been developed and manufactured by LLC SPC Athlon Avia since 2014. Within 2019-2020, the UAS passed a full spectrum of state tests and was adopted by the Armed Forces of Ukraine. The main criteria that this UAS meets are the detection and tracking of enemy objectives, equipment maintenance and target  reconnaissance. Among the peculiarities of UAV application are  performance of tasks in adverse meteorological conditions, the use of radio-electronic suppression by the opposing parties, significant spatial characteristics of the areas of responsibility of units and subdivisions for reconnaissance and engagement. The change in the charge current of the battery depending on the air temperature and the change in the charge current of the battery depending on the wind speed in different meteorological conditions were analyzed  in the article. The article presents experimental results that determine the order of current consumption for battery time depending on meteorological factors, such as wind speed and air temperature. These results indicate that the UAV A1-CM Furia during the task accomplishment  can not meet the flight characteristics that are defined in the flight operation manual UAS (FAM). The FAM does not separate the differences in the use of UAV  in different meteorological conditions. This causes possible errors in calculating the maximum length of the route and the maximum possible time in the air.  In the article it was proposed to develop a correction  for the use of UAV depending on changes in wind speed and temperature . During the assessing of possible corrections for the use of UAV at different wind speeds and air temperatures, the accuracy of determining the possible values of the maximum route length and maximum time of UAV in the air allows us to calculate more accurate data for future tasks accomplisment. Experimental methods of calculating corrections took a large part in the specific study of information without taking into account the real meteorological conditions while planning the flight task of the UAV A1-CM Furia. The obtained results show that without further consideration of meteorological conditions while planning a flight task there may be inaccuracies.

scholarly journals NEURAL NETWORKS FOR THE SIMULATION OF MICROCLIMATIC PARAMETERS IN DAIRY HOUSES

2009 ◽  
Vol 40 (2) ◽  
pp. 45
Author(s):  
Alessandro D'Emilio ◽  
Rosari Mazzarella ◽  
Simona M.C. Porto
Keyword(s):  
Wind Speed ◽  
Air Temperature ◽  
Parametric Analysis ◽  
Natural Ventilation ◽  
Outdoor Air ◽  
Adequate Accuracy ◽  
Temperature And Humidity ◽  
Air Speed ◽  
Artificial Neural Network Ann ◽  
Range Of Values

The aim of the present paper is to study natural ventilation in a dairy house by means of a parametric analysis relating wind speed and direction to the air flows through the ridge vent of the building. This analysis was carried out by means of an artificial neural network (ANN) which capability in modelling and simulating some climatic parameters inside a dairy house has been validated using the data collected in a trial carried out during summer 2005. The results show that modelling a Generalized feed-forward Multi-Layer Perceptron ANN allowed to obtain satisfactory results in the simulation of air speed and direction and air temperature and humidity inside a dairy house, using as input the values of wind speed and direction and outdoor air temperature and humidity. The adequate accuracy in the simulation of the air motion across the ridge vent allowed to perform a parametric analysis of the ventilation, which provided the values of air speed and direction in function of a fixed range of values of wind speed and direction.

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