Correction to “[Comparison of Atmospheric Stability at Wind Observation Tower Height and Hub/Rotor Height Using 200 m Meteorological Observation Tower Data

In computational fluid dynamics (CFD) models, it is generally assumed that the atmospheric stability is constant throughout the entire domain. Furthermore, CFD models perform simulations for each wind direction separately. However, atmospheric stability, both onshore and offshore, varies daily and also exhibits diurnal variation. In this study, using 9 years of data from a 200‐m high meteorological mast, we investigated the differences in atmospheric stability calculated at altitudes below the hub height and at hub/rotor heights for 16 wind directions. The following findings were obtained. The investigation of 16 wind directions revealed significant differences in the Richardson number obtained from meteorological variables at 10‐ and 50‐m heights, which correspond to typical wind observation tower heights in Japan, and those obtained at 100‐ and 150‐m heights, which correspond to the current hub and rotor heights. The frequency of stable conditions followed the order: current hub and rotor heights > future hub and rotor heights (calculated using meteorological variables at 150‐ and 200‐m heights) > wind observation tower heights. The comparison of the occurrence frequency of atmospheric stability between the current hub height/rotor height (100 to 150 m) and the future hub height/rotor height (150 to 200 m) revealed differences in the frequency of stable conditions. Investigation using the temperature lapse rate showed that the stable layer is weaker at the future hub/rotor height compared with the current hub/rotor height.

The purpose of this research is to experimentally identify the performance of most of the light-weight observation towers open for public in Latvia. It analyzes the structure of towers, technical condition, dynamic parameters and dynamic response to human movement along the tower height. During the experiment there were measured and recorded the vibration accelerations of 18 observation towers’ upper platform. Further dynamic parameters were extracted using the spectral analysis. There was performed the sensitivity analysis to establish parameters that most influences the dynamic response amplitudes due to human movement. All experimentally obtained fundamental frequencies of the inspected towers are in the typical range of human walking frequencies. It is found that the main parameter that denotes the response level (acceleration amplitude) of the tower due to human movement is a tower self-weight.

Aerodynamic drag coefficient over equatorial coastal industrialized and urban areas

In this study we examine the applicability of the Mini Doppler Sodar as an instrument evaluating wind characteristics for constructing a wind farm. The data obtained from the Mini Doppler Sodar were compared with those of the 70 m observation tower at Hoiyo Sand Dune, where is known to be windy and to be expected constructing a wind farm. The Mini Doppler Sodar gave the wind speed and direction almost the same with those by the tower at each height. When land breeze blew, the Mini Doppler Sodar data agreed with the Tower data, but disagreed at the other times, because of sound noises and turbulence in a convective boundary layer. The data are however able to be compensated by using a regression line. The Mini Doppler Sodar will be suitable for the assessment of wind characteristics after some improvements.

Measurements and simulations of energy fluxes over a high-rise and compact urban area in Hong Kong

Recently, the industry using unmanned aerial vehicle (UAV) is rapidly growing. Accordingly, researches on the relevant issues including urban meteorology are being actively conducted. However, concerns about the reliability of observation sensors used in meteorological monitoring equipped with drones highlight the need for further research. The Boseong Standard Meteorological Observatory’s comprehensive observation tower, situated in flat and homogeneous terrain without tall buildings nearby, is an ideal site to verify the reliability of UAV observation data.In this study, the reliability of UAV meteorological observations is quantitatively verified by comparing the UAV-observed meteorological factors with measurements from the Boseong observation tower. Observations were conducted from January 20 to 22, 2025, using a UAV with an iMET-X4 temperature and humidity sensor and an FT742-SM wind speed and direction sensor. A total of 39 flights were performed, including stationary flights at altitudes of 300, 80, 60, 40, 20, and 10m for 150 seconds each. To analyze turbulence characteristics, additional stationary flights at 300 and 80m for 930 seconds each were performed.The reliability of UAV meteorological observations was evaluated by comparing vertical meteorological data between UAV and towers and statistically analyzing the accuracy of UAV observation data. In addition to standard variables such as wind and temperature, we expect that production of post-processed observation data such as turbulent intensity can also be obtained using the UAV meteorological observation.This research utilized data from the "Standardization of National Meteorological Equipment and Observation Data" project by the Korea Meteorological Administration's National Institute of Meteorological Sciences and was supported by the "Development of Core Technologies for Safe Operation of Korean Urban Air Mobility (K-UAM)" (RS-2024-00404042) project funded by the Korea Meteorological Administration. And this work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT) (RS-2024-00356913).

In this study, we measured evapotranspiration in an evergreen broadleaf forest watershed in the Kampong Thom Province of central Cambodia with the aid of a 60‐m high meteorological observation tower. The main vegetation species at the study site were Myristica iners and Vatica odorata. The mean tree height in the upper crown layer at the study site was 27·2 m, and the maximum tree height was 45·1 m. A heat balance method, which incorporated the Bowen ratio, was used to calculate the energy balance above the forest canopy; this value was subsequently used for the calculation of evapotranspiration. All the equipment necessary for the measurement of meteorological variables was installed in the observation tower. Data were collected during two distinct sampling periods: October 2003, in the late rainy season, and March 2004, in the middle of the dry season. Daily variations in evapotranspiration were strongly correlated with the measured amount of net radiation above the canopy layer. On the basis of our measurements, the mean evapotranspiration levels of the forest watershed during the late rainy season and the middle of the dry season were 4·3 and 4·6 mm/day, respectively. No significant differences in soil moisture were observed between the middle of the dry season and the late rainy season, probably due to the shallow depth of the water table. The results of this study suggest that the high levels of evapotranspiration recorded during the middle of the dry season reflect the presence of sufficient soil moisture (derived from the shallow water table) and a high vapour‐pressure deficit. Copyright © 2008 John Wiley & Sons, Ltd.

Annular tuned liquid dampers (TLDs) may be installed in slender structures with limited floor space, in which people and utilities must pass through the core, such as a wind turbine or observation tower. This study investigates an annular-shaped TLD equipped with damping screens. A linearized equivalent mechanical model capable of capturing the fundamental sloshing mode response of an annular TLD is presented. An experimental shake table testing program is completed to assess the performance of the model. Thirty-six frequency sweep tests consisting of various TLD configurations, excitation amplitudes, and excitation directions are completed. Good agreement is observed between the linearized equivalent mechanical model and experimental wave heights, sloshing forces, and energy dissipated per cycle that have been filtered to include only the fundamental sloshing mode response. The model is also observed to be in good agreement with experimental data for different excitation directions. The model is coupled to a generalized structure to investigate the response of a structure equipped with an annular TLD. The annular TLD is found to reduce the response of a generalized offshore wind turbine structure undergoing harmonic force excitation. The annular TLD provides performance comparable to an optimal linear tuned mass damper (TMD) with the same properties for a range of force excitation amplitudes.

Vertical distributions of suspended particles and their components as measured on a meteorological observation tower

The vertical distributions of the water vapor mixing ratio (w) were measured by Raman lidar at the Meteorological Research Institute, Japan, in 2000 to 2004. The measured values were compared with those obtained with radiosondes, hygrometers on the meteorological observation tower, and Global Positional System (GPS) antennas. The values of w obtained with the lidar agreed within 9% with those obtained with the Meisei RS2-91 radiosonde for w > 0.5 g/kg^-1. However, they were systematically higher than those obtained with the Vaisala RS80-A radiosonde for that region. The vertical variations of w obtained with the lidar were similar to those obtained with the Meisei RS-01G and Meteolabor Snow White radiosondes for w > 0.3 g/kg^-1. The temporal variations of w obtained with the lidar were similar to those obtained with the hygrometers at heights between 50 and 213 m on the tower, although the absolute values differed systematically due to the incomplete overlap of the laser beam and the receiver's field of view at the lower heights. The precipitable water vapor content obtained with the lidar generally agreed with those obtained with GPS, except for the period when the large spatial inhomogeneity of w was present.

The concentration of mercury in airborne particles was determined in samples collected at heights of 1m and at 175m up the Meteorological Observation Tower (213m) at the Meteorological Research Institute, Tsukuba between August 1985 and April 1986. The concentrations of particulate mercury at the two heights were compared with gaseous mercury levels at a height of 10m and with other chemical components in the particles. The concentrations of particulate mercury at both heights showed no positive correlation with those of gaseous mercury, total suspended particles, sulfate, chloride, sodium or calcium. However, there was some positive correlation between particulate mercury and nitrate concentrations especially at 175m; the concentrations of these components were found to be high when the wind direction was southwesterly. These results suggest that these components were transported from the Tokyo Metropolitan area.

The vertical distribution profiles of the water vapor mixing ratio (w) were measured by Raman lidar at the Meteorological Research Institute, Japan, during the period from 2000 to 2004. The measured values were compared with those obtained with radiosondes, hygrometers on a meteorological observation tower, and global positioning system (GPS) antennas near the lidar site. The values of w obtained with the lidar were lower than those obtained with the corrected Meisei RS2-91 radiosonde by 1.2% on average and higher than those obtained with the corrected Vaisala RS80-A radiosonde by 17% for w ≥ 0.5 g kg−1. The lidar data were higher than those radiosondes’ data by 19% or 33% for w < 0.5 g kg−1. The vertical variations of w obtained with the lidar differed from those obtained with the Meisei RS-01G radiosonde and Meteolabor Snow White radiosonde by 5% on average for w ≥ 0.5 g kg−1. The lidar data were lower than those radiosondes’ data by 37% or 39% for w < 0.5 g kg−1. The temporal variations of w obtained with the lidar and the hygrometers on the meteorological tower agreed to within 0.4% at a height of 213 m, although the absolute values differed systematically by 9%–14% due to the incomplete overlap of the laser beam and the receiver’s field of view at heights between 50 and 150 m. The precipitable water vapor obtained with the lidar indicated a mean positive bias of 2 mm (9%–11%) relative to those obtained with GPS. The lidar water vapor calibration coefficient that was calculated using RS2-91 radiosonde data varied by 11% during an 18-month period. Therefore, it is necessary to develop an accurate, yet convenient, method for determining the calibration coefficient for the use of the lidar.

South Korea is surrounded by the sea on three sides. The characteristics of offshore wind resources vary from region to region due to the influence of the distribution of the coastline and differences in roughness length and atmospheric stability between the coast and the sea. In particular, turbulent gusts and low-level wind shear occurring near the hub height of the wind turbine within the atmospheric boundary layer have a significant effect on the load of wind turbines. These severe weather phenomena are closely related to atmospheric stability. Therefore, the objective of this study is to determine differences in wind resource characteristics in the South Korean offshore and coast in relation to variations in atmospheric stability using observation data from the HeMOSU-1 meteorological tower in the West Sea and the Boseong meteorological observation tower on the southern coast. On the southern coast, changes in sea and land breezes are observed throughout diurnal and nocturnal periods, with an atmospheric stability distribution similar to that of land, which is unstable during the day and becomes more stable at night. On the other hand, the stable ratio continues to dominate in the west offshore. In the case of coastal areas, low-level wind shear occasionally occurs near the general wind turbine hub height approximately over 100 m due to the influence of winds from the sea. This study shows that when constructing an offshore wind farm, it is necessary to first analyze the characteristics of local coastal and offshore wind resources for more efficient and safe wind farm construction and operation.

Observational study of typhoon effects on the oval-shaped 330 m high Zhuhai Center Tower

A meteorological observation tower at Tsukuba Science City is equipped with mean wind, temperature and humidity sensors, together with instruments for the measurement of their short period fluctuations at seven levels (including the top of the tower) ranging from 10 m to 213 m above the base of the tower. The general statistical properties of wind data for one year are discussed in this paper together with the tower facilities including the data acquisition system. The annual arithmetic mean wind speeds increase from 3.14 m/s at the 25 m level to 6.09 m/s at the top level. The annual mean wind speed at the 25 m level is highest during the daytime and one at the 213 m level at night. Monthly relative frequency distribution of wind speed can be well simulated with Weibull distribution. Annual relative frequency of wind direction has three clear peaks, which are very similar to the climatological data obtained at the Tateno Aerological Observatory near the Meteorological Research Institute. The characteristics of vector wind speed are examined and the monthly mean profiles from May to September seem to be explained by the geostrophic wind. The power spectra of wind speed in summer and fall have a remarkable peak of daily cycle and a relatively large peak with 3-4 days period in winter and spring.