Adaptive Thermal Image Velocimetry of spatial wind movement on landscapes using near target infrared cameras

Abstract. Thermal Image Velocimetry (TIV) is a near-target remote sensing technique for estimating two- dimensional near-surface wind velocity based on spatiotemporal displacement of fluctuations in surface brightness temperature captured by an infrared camera. The addition of an automated parameterization and the combination of ensemble TIV results into one output made the method more suitable to changing meteorological conditions and less sensitive to noise stemming from the airborne sensor platform. Three field campaigns were carried out to evaluate the algorithm over turf, dry grass and wheat stubble. The derived velocities were validated with independently acquired observations from fine wire thermocouples and sonic anemometers. It was found that the TIV technique correctly derives atmospheric flow patterns close to the ground. Moreover, the modified method resolves wind speed statistics close to the surface at a higher resolution than the traditional measurement methods. Adaptive Thermal Image Velocimetry (A-TIV) is capable of providing contact-less spatial information about near-surface atmospheric motion and can help to be a useful tool in researching turbulent transport processes close to the ground.

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Application of the Thermal Image Velocimetry to Measure and Visualize Spatial Distribution of Near Surface Wind

JOURNAL OF JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES ◽

10.3178/jjshwr.29.186 ◽

2016 ◽

Vol 29 (3) ◽

pp. 186-195

Author(s):

Atsushi INAGAKI

Keyword(s):

Spatial Distribution ◽

Surface Wind ◽

Thermal Image ◽

Near Surface ◽

Image Velocimetry

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ESTIMATING NEAR-SURFACE WIND FIELD BY AERIAL THERMAL IMAGE VELOCIMETRY

Journal of Japan Society of Civil Engineers Ser B1 (Hydraulic Engineering) ◽

10.2208/jscejhe.73.i_457 ◽

2017 ◽

Vol 73 (4) ◽

pp. I_457-I_462

Author(s):

Motoyuki HIJIKATA ◽

Atsushi INAGAKI ◽

Manabu KANDA ◽

Yukihiko YAMASHITA

Keyword(s):

Wind Field ◽

Surface Wind ◽

Thermal Image ◽

Near Surface ◽

Image Velocimetry ◽

Surface Wind Field

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Experiments on wind-driven heat exchange processes over melting snow

10.5194/egusphere-egu21-10182 ◽

2021 ◽

Author(s):

Michael Haugeneder ◽

Tobias Jonas ◽

Dylan Reynolds ◽

Michael Lehning ◽

Rebecca Mott

Keyword(s):

Snow Cover ◽

Surface Wind ◽

Infrared Camera ◽

Snow Accumulation ◽

Internal Boundary ◽

Small Scale ◽

Snow Melt ◽

Two Dimensional ◽

Atmospheric Conditions ◽

Near Surface

Snowmelt runoff predictions in alpine catchments are challenging because of the high spatial variability of the snow cover driven by various snow accumulation and ablation processes. In spring, the coexistence of bare and snow-covered ground engages a number of processes such as the enhanced lateral advection of heat over partial snow cover, the development of internal boundary layers, and atmospheric decoupling effects due to increasing stability at the snow cover. The interdependency of atmospheric conditions, topographic settings and snow coverage remains a challenge to accurately account for these processes in snow melt models. In this experimental study, we used an Infrared Camera (VarioCam) pointing at thin synthetic projection screens with negligible heat capacity. Using the surface temperature of the screen as a proxy for the air temperature, we obtained a two-dimensional instantaneous measurement. Screens were installed across the transition between snow-free and snow-covered areas. With IR-measurements taken at 10Hz, we capture the dynamics of turbulent temperature fluctuations over the patchy snow cover at high spatial and temporal resolution. From this data we were able to obtain high-frequency, two-dimensional windfield estimations adjacent to the surface.Preliminary results show the formation of a stable internal boundary layer (SIBL), which was temporally highly variable. Our data suggest that the SIBL height is very shallow and strongly sensitive to the mean near-surface wind speed. Only strong gusts were capable of penetrating through this SIBL leading to an enhanced energy input to the snow surface.With these type of results from our experiments and further measurements this spring we aim to better understand small scale energy transfer processes over patch snow cover and it&#8217;s dependency on the atmospheric conditions, enabling to improve parameterizations of these processes in coarser-resolution snow melt models.

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Environmental Control of Phytoplankton Patchiness

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f81-085 ◽

1981 ◽

Vol 38 (6) ◽

pp. 638-641 ◽

Cited By ~ 17

Author(s):

Jean-Claude Therriault ◽

Trevor Platt

Keyword(s):

Production Efficiency ◽

Environmental Control ◽

Turbulent Transport ◽

Physicochemical Characteristics ◽

Transport Processes ◽

Physical Factors ◽

Near Surface ◽

Coastal Embayment ◽

High Winds ◽

Dynamic Fluctuation

The relative importance of the various biological, chemical, and physical factors for the control of the phytoplankton patchiness in the environment has been studied for the near-surface waters of a small coastal embayment. It was found that during periods of low turbulent mixing (wind speed [Formula: see text]), the phytoplankton patchiness was induced by local differences (taxonomic or physiological) in its production efficiency which was linked to the dynamic fluctuation in the physicochemical characteristics of the medium. For periods of high winds [Formula: see text] it is indicated that the physical turbulent transport processes were responsible for damping out the spatial variations in the phytoplankton distribution.Key words: phytoplankton biomass, P/B ratio, spatial distribution, turbulence, wind stress

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Space-borne radar observation of near-surface wind effect on anomalously highly-directional backscattering of radio waves from Aeolian processes of sand and dust transporting in desert regions

Ukrainian journal of remote sensing ◽

10.36023/ujrs.2020.24.162 ◽

2020 ◽

pp. 4-8

Author(s):

Dmitro Bychkov ◽

Viktor Ivanov ◽

Aleksandr Matveyev ◽

Valeriy Tsymbal ◽

Sergey Yatsevich

Keyword(s):

Remote Sensing ◽

Surface Wind ◽

Transport Processes ◽

Dust Particles ◽

Radio Waves ◽

Near Surface ◽

Radar Remote Sensing ◽

Aeolian Processes ◽

Dust Transport ◽

Desert Regions

Aeolian process of sand and dust transporting is known to form the near-ground surface structures over vast territories and fill the atmosphere up with suspended aerosols-like dust particles which are spread then by winds over long distances. The presence of atmospheric dust in the planet's environment is one of the factors affecting the temperature and climatic conditions of vast regions of the Earth. A number of publications (Ivanov et al., 2015; Ivanov et al., 2016; Ivanov et al., 2016; Ivanov et al., 2018) analyze the revealed effect of anomalously highly(narrow) directed backscattering of radio waves which manifests itself in radar remote sensing (in range of local irradiation angles θ ≈ 31°÷32°) in areas covered with deep sand. At the same time, there is no specific data available from published studies investigating the impact of the near-surface wind on anomalously highly-directional backscattering of radio waves based on the results of radar remote sensing researches of Aeolian sand and dust transport processes in desert regions that, in turn, could have been used later to determine the parameters of such transport process. This article presents the results of analysis of the data obtained from long-term studies of desert regions of El-Djuf, Akshar and Trarza in Mauritania by means of space-borne SAR Envisat-1. The purpose of the analysis was actually to identify the specifics of the effect that the near-surface wind has on the anomalously highly-directional backscattering of radio waves which is identified by radar based researches of Aeolian processes of sand and dust transport in desert regions, so can be used for remote determination of such transportation parameters.

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Transient Cold Air Drainage down a Shallow Valley

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-14-0010.1 ◽

2014 ◽

Vol 71 (7) ◽

pp. 2534-2544 ◽

Cited By ~ 15

Author(s):

L. Mahrt ◽

Jielun Sun ◽

S. P. Oncley ◽

T. W. Horst

Keyword(s):

Surface Wind ◽

Vertical Mixing ◽

Cold Pool ◽

Drainage Flow ◽

Wind Maximum ◽

Near Surface ◽

Cold Air ◽

Vertical Scale ◽

Sonic Anemometers ◽

Small Valley

Abstract Drainage of cold air down a small valley and associated near-surface wind maxima are examined from 20 stations with sonic anemometers at 1 m and from a 20-m tower that includes six sonic anemometers in the lowest 5 m, deployed in the Shallow Cold Pool Experiment (SCP). The small valley is about 270 m wide and 12 m deep with a downvalley slope of 2%–3%. The momentum budget indicates that the flow is driven by the buoyancy deficit of the flow and opposed primarily by the stress divergence while the remaining terms are estimated to be at least an order of magnitude smaller. This analysis also reveals major difficulties in quantifying such a budget due to uncertainties in the measurements, sensitivity to choice of averaging time, and sensitivity to measurement heights. Wind maxima occur as low as 0.5 m in the downvalley drainage flow—the lowest observational level. The downvalley cold air drainage and wind maxima are frequently disrupted by transient modes that sometimes lead to significant vertical mixing. On average, the downvalley drainage of cold air occurs with particularly weak turbulence with stronger turbulence above the drainage flow. The momentum flux profile responds to the shear reversal at the wind maximum on a vertical scale of 1 m or less, suggesting the important role of finescale turbulent diffusion.

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Recurrence Characteristics Analysis of Near-Surface Wind Speed Signal with Different Sampling Frequencies

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.599-601.1605 ◽

2014 ◽

Vol 599-601 ◽

pp. 1605-1609 ◽

Cited By ~ 1

Author(s):

Ming Zeng ◽

Zhan Xie Wu ◽

Qing Hao Meng ◽

Jing Hai Li ◽

Shu Gen Ma

Keyword(s):

Wind Speed ◽

Surface Wind ◽

Surface Wind Speed ◽

Recurrence Plot ◽

Sampling Frequency ◽

Near Surface ◽

Gas Leakage ◽

Time Period ◽

Characteristics Analysis ◽

Quantification Analysis

The wind is the main factor to influence the propagation of gas in the atmosphere. Therefore, the wind signal obtained by anemometer will provide us valuable clues for searching gas leakage sources. In this paper, the Recurrence Plot (RP) and Recurrence Quantification Analysis (RQA) are applied to analyze the influence of recurrence characteristics of the wind speed time series under the condition of the same place, the same time period and with the sampling frequency of 1hz, 2hz, 4.2hz, 5hz, 8.3hz, 12.5hz and 16.7hz respectively. Research results show that when the sampling frequency is higher than 5hz, the trends of recurrence nature of different groups are basically unchanged. However, when the sampling frequency is set below 5hz, the original trend of recurrence nature is destroyed, because the recurrence characteristic curves obtained using different sampling frequencies appear cross or overlapping phenomena. The above results indicate that the anemometer will not be able to fully capture the detailed information in wind field when its sampling frequency is lower than 5hz. The recurrence characteristics analysis of the wind speed signals provides an important basis for the optimal selection of anemometer.

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Evaluation of HRCLDAS and ERA5 Datasets for Near-Surface Wind over Hainan Island and South China Sea

Atmosphere ◽

10.3390/atmos12060766 ◽

2021 ◽

Vol 12 (6) ◽

pp. 766

Author(s):

Yi Jiang ◽

Shuai Han ◽

Chunxiang Shi ◽

Tao Gao ◽

Honghui Zhen ◽

...

Keyword(s):

South China Sea ◽

South China ◽

Surface Wind ◽

Hainan Island ◽

The South China Sea ◽

Wind Data ◽

The South ◽

Near Surface ◽

China Sea

Near-surface wind data are particularly important for Hainan Island and the South China Sea, and there is a wide range of wind data sources. A detailed understanding of the reliability of these datasets can help us to carry out related research. In this study, the hourly near-surface wind data from the High-Resolution China Meteorological Administration (CMA) Land Data Assimilation System (HRCLDAS) and the fifth-generation ECMWF atmospheric reanalysis data (ERA5) were evaluated by comparison with the ground automatic meteorological observation data for Hainan Island and the South China Sea. The results are as follows: (1) the HRCLDAS and ERA5 near-surface wind data trend was basically the same as the observation data trend, but there was a smaller bias, smaller root-mean-square errors, and higher correlation coefficients between the near-surface wind data from HRCLDAS and the observations; (2) the quality of HRCLDAS and ERA5 near-surface wind data was better over the islands of the South China Sea than over Hainan Island land. However, over the coastal areas of Hainan Island and island stations near Sansha, the quality of the HRCLDAS near-surface wind data was better than that of ERA5; (3) the quality of HRCLDAS near-surface wind data was better than that of ERA5 over different types of landforms. The deviation of ERA5 and HRCLDAS wind speed was the largest along the coast, and the quality of the ERA5 wind direction data was poorest over the mountains, whereas that of HRCLDAS was poorest over hilly areas; (4) the accuracy of HRCLDAS at all wind levels was higher than that of ERA5. ERA5 significantly overestimated low-grade winds and underestimated high-grade winds. The accuracy of HRCLDAS wind ratings over the islands of the South China Sea was significantly higher than that over Hainan Island land, especially for the higher wind ratings; and (5) in the typhoon process, the simulation of wind by HRCLDAS was closer to the observations, and its simulation of higher wind speeds was more accurate than the ERA5 simulations.

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