scholarly journals High frequency observation during the sand and dust storms in the Qingtu Lake Observatory

2021 ◽  
Author(s):  
Xuebo Li ◽  
Yongxiang Huang ◽  
Guohua Wang ◽  
Xiaojing Zheng
Keyword(s):  
High Frequency ◽  
Power Analysis ◽  
Isotropic Turbulence ◽  
Sonic Anemometer ◽  
Sampling Frequency ◽  
Dust Storms ◽  
Scaling Exponent ◽  
Detailed Measurement ◽  
Frequency Observation ◽  
Dust Monitor

Abstract. Partially due to the global climate change, the sand and dust storms (SDS) occurred more and more frequently, yet a detailed measurement of the SDS event at different heights is still lacking. Here we provide a high frequency observation in the Qingtu Lake Observation Array (QLOA), China. The wind and dust information were measured simultaneously at different wall-normal heights during the SDS process. The datasets span the period from 17 March to 9 June 2016. The wind speed and direction are recorded by a sonic anemometer with a sampling frequency 50 Hz, while the particulate matter 10 (PM10) is sampled simultaneously by a dust monitor with a sampling frequency 1 Hz. The wall-normal array had 11 sonics and monitors spaced logarithmically from z = 0.9 to 30 m, where the spacing is about 2-meter between the sonic anemometer and dust monitor at the same height. Based on its non-stationary feature, the SDS event can be divided into three stages, i.e., ascending, stabilizing and descending stages, in which the dynamic mechanism of the wind and dust fields might be different. This is preliminarily characterized via the classical Fourier power analysis. Temporal evolution of the scaling exponent from Fourier power analysis suggests slightly below the classical Kolmogorov value of −5/3 for the three-dimensional homogeneous and isotropic turbulence. During the stabilizing stage, the collected PM10 shows a very intermittent pattern, which can be further linked with the burst events in the turbulent atmospheric boundary layer. This dataset is valuable for a better understanding the SDS dynamics, which has being publicly available at Zenodo through the DOI 10.5281/zenodo.5034196 (Li et al., 2021a).

scholarly journals High-frequency observation during sand and dust storms at the Qingtu Lake Observatory

2021 ◽  
Vol 13 (12) ◽  
pp. 5819-5830
Author(s):  
Xuebo Li ◽  
Yongxiang Huang ◽  
Guohua Wang ◽  
Xiaojing Zheng
Keyword(s):  
High Frequency ◽  
Power Analysis ◽  
Sonic Anemometer ◽  
Sampling Frequency ◽  
Dust Storms ◽  
Scaling Exponent ◽  
Detailed Measurement ◽  
Sonic Anemometers ◽  
Frequency Observation ◽  
Dust Monitor

Abstract. Partially due to global climate change, sand and dust storms (SDSs) have occurred more and more frequently, yet a detailed measurement of SDS events at different heights is still lacking. Here we provide a high-frequency observation from the Qingtu Lake Observation Array (QLOA), China. The wind and dust information were measured simultaneously at different wall-normal heights during the SDS process. The datasets span the period from 17 March to 9 June 2016. The wind speed and direction are recorded by a sonic anemometer with a sampling frequency of 50 Hz, while particulate matter with a diameter of 10 µm or less (PM10) is sampled simultaneously by a dust monitor with a sampling frequency of 1 Hz. The wall-normal array had 11 sonic anemometers and monitors spaced logarithmically from z=0.9 to 30 m, where the spacing is about 2 m between the sonic anemometer and dust monitor at the same height. Based on its nonstationary feature, an SDS event can be divided into three stages, i.e., ascending, stabilizing and descending stages, in which the dynamic mechanism of the wind and dust fields might be different. This is preliminarily characterized by the classical Fourier power analysis. Temporal evolution of the scaling exponent from Fourier power analysis suggests a value slightly below the classical Kolmogorov value of -5/3 for the three-dimensional homogeneous and isotropic turbulence. During the stabilizing stage, the collected PM10 shows a very intermittent pattern, which can be further linked with the burst events in the turbulent atmospheric boundary layer. This dataset is valuable for a better understanding of SDS dynamics and is publicly available in a Zenodo repository at https://doi.org/10.5281/zenodo.5034196 (Li et al., 2021a).

Energy Transfer in a Linear Turbulence Model

2018 ◽  
Author(s):  
Bendegúz Dezső Bak ◽  
Tamás Kalmár-Nagy
Keyword(s):  
Energy Transfer ◽  
Energy Spectrum ◽  
Isotropic Turbulence ◽  
Mechanistic Model ◽  
Viscous Friction ◽  
Scaling Exponent ◽  
Engineering Systems ◽  
Simple Method ◽  
The Masses ◽  
Binary Tree Structure

Energy transfer is present in many natural and engineering systems which include different scales. It is important to study the energy cascade (which refers to the energy transfer among the different scales) of such systems. A well-known example is turbulent flow in which the kinetic energy of large vortices is transferred to smaller ones. Below a threshold vortex scale the energy is dissipated due to viscous friction. We introduce a mechanistic model of turbulence which consists of masses connected by springs arranged in a binary tree structure. To represent the various scales, the masses are gradually decreased in lower levels. The bottom level of the model contains dampers to provide dissipation. We define the energy spectrum of the model as the fraction of the total energy stored in each level. A simple method is provided to calculate this spectrum in the asymptotic limit, and the spectra of systems having different stiffness distributions are calculated. We find the stiffness distribution for which the energy spectrum has the same scaling exponent (−5/3) as the Kolmogorov spectrum of 3D homogeneous, isotropic turbulence.

scholarly journals Turbulence fluxes and variances measured with a sonic anemometer mounted on a tethered balloon

2016 ◽  
Vol 9 (9) ◽  
pp. 4375-4386 ◽  
Author(s):  
Guylaine Canut ◽  
Fleur Couvreux ◽  
Marie Lothon ◽  
Dominique Legain ◽  
Bruno Piguet ◽  
...  
Keyword(s):  
Boundary Layer ◽  
High Frequency ◽  
Field Experiments ◽  
Sonic Anemometer ◽  
Motion Sensor ◽  
Tethered Balloon ◽  
Inertial Motion ◽  
Convective Boundary ◽  
Momentum Fluxes ◽  
Field Campaigns

Abstract. This study presents the first deployment in field campaigns of a balloon-borne turbulence probe, developed with a sonic anemometer and an inertial motion sensor suspended below a tethered balloon. This system measures temperature and horizontal and vertical wind at high frequency and allows the estimation of heat and momentum fluxes as well as turbulent kinetic energy in the lower part of the boundary layer. The system was validated during three field experiments with different convective boundary-layer conditions, based on turbulent measurements from instrumented towers and aircraft.

scholarly journals Useful parameters for the motion analysis of facial skin care in Japanese women

2020 ◽  
Vol 39 (1) ◽  
Author(s):  
Shingo Sakai ◽  
Ruako Takatori ◽  
Mika Nomura ◽  
Kuniaki Uehara
Keyword(s):  
High Frequency ◽  
Frequency Component ◽  
Japanese Women ◽  
Skin Care ◽  
Autonomic Nerve ◽  
Psychological State ◽  
High Frequency Component ◽  
Scaling Exponent ◽  
Back Side ◽  
Facial Skin

Abstract Background Facial skin care (FSC) is an important routine for Japanese women. Hand motions during FSC physically affect psychological state. However, it is very difficult to evaluate hand motions during personal and complex FSC. The objective of this study was to find out objective and quantitative parameters for hand motions during facial skin care (FSC). Women who enjoy and soothe during FSC (Enjoyment group (E group), n = 20) or not (non-enjoyment group (NE group), n = 19) were recruited by an advance questionnaire. The same lotion, emulsion, and cream were provided to all subjects, and they used sequentially in the same way as the women’s daily FSC. The motion of the marker on the back side of the right middle finger during FSC was tracked by a motion capture system. The heart rate variability (HRV) was also measured before and after FSC for evaluating psychological effect. Results The averaged acceleration (Avg. ACC), approximate entropy (ApEn), and power law scaling exponent (Rest γ) of the cumulative duration of slow motion from the sequential data of acceleration were evaluated. Compared to the NE group, the E group showed a lower Avg. ACC when using emulsion (p = 0.005) and cream (p = 0.007), a lower ApEn when using emulsion (p = 0.003), and a lower Rest γ (p = 0.024) when using all items, suggesting that compared to the NE group, the E group had more tender and regular motion, and sustainable slow motions, especially in the use of emulsion. In the E group, the low/high-frequency component of HRV decreased significantly after FSC, suggesting suppression of sympathetic activity (p = 0.045). NE group did not. For all subjects, ApEn and Rest γ showed significantly positive correlation with the increase in the low/high-frequency component of HRV after FSC (p < 0.01). ApEn showed significantly negative correlation with the increase in the high-frequency component of HRV after FSC (p < 0.05). Avg. ACC did not show significant correlation with them. These results suggested that the behavior of FSC influences the autonomic nerve system. Conclusions ApEn and Rest γ are useful parameters for evaluating quality of hand motions during FSC.

Scaling exponent values as an ordinary function of the ratio of very low frequency to high frequency powers in heart rate variability over various sleep stages

2016 ◽  
Vol 20 (3) ◽  
pp. 975-985 ◽  
Author(s):  
Ren-Jing Huang ◽  
Ching-Hsiang Lai ◽  
Shin-Da Lee ◽  
Wei-Che Wang ◽  
Ling-Hui Tseng ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
High Frequency ◽  
Low Frequency ◽  
Sleep Stages ◽  
Scaling Exponent ◽  
Very Low Frequency

scholarly journals BVOC ecosystem flux measurements at a high latitude wetland site

2008 ◽  
Vol 8 (6) ◽  
pp. 21129-21169 ◽  
Author(s):  
T. Holst ◽  
A. Arneth ◽  
S. Hayward ◽  
A. Ekberg ◽  
M. Mastepanov ◽  
...  
Keyword(s):  
High Frequency ◽  
Boreal Forests ◽  
Sonic Anemometer ◽  
Proton Transfer Reaction ◽  
Heat Fluxes ◽  
Emission Rates ◽  
Water Vapour Concentration ◽  
Process Understanding ◽  
Emission Fluxes ◽  
Ecosystem Flux

Abstract. In this study, we present summertime concentrations and fluxes of biogenic volatile organic compounds (BVOCs) measured at a sub-arctic wetland in northern Sweden using a disjunct eddy-covariance (DEC) technique based on a proton transfer reaction mass spectrometer (PTR-MS). The vegetation at the site was dominated by Sphagnum, Carex and Eriophorum spp. The performance of the DEC system was assessed by comparing H3O+-ion cluster formed with water molecules (H3O+(H2O) at m37) with water vapour concentration measurements made using an adjacent humidity sensor, and from a comparison of sensible heat fluxes for high frequency and DEC data obtained from the sonic anemometer. These analyses showed no significant PTR-MS sensor drift over a period of several weeks and only a small flux-loss due to high-frequency spectrum omissions. This loss was within the range expected from other studies and the theoretical considerations. Standardised (20°C and 1000 μmol m−2 s−1 PAR) summer isoprene emission rates of 323 μg C m−2 (ground area) h−1 were comparable with findings from more southern boreal forests, and fen-like ecosystems. On a diel scale, measured fluxes indicated a stronger temperature dependence when compared with emissions from temperate or (sub)tropical ecosystems. For the first time, to our knowledge, we report ecosystem methanol fluxes from a sub-arctic ecosystem. Maximum daytime emission fluxes were around 270 μg m−2 h−1 (ca. 100 μg C m−2 h-1) and measurements indicated some nocturnal deposition. The measurements reported here covered a period of 50 days (1 August to 19 September 2006), approximately one half of the growing season at the site, and allowed to investigate the effect of vegetation senescence on daily BVOC fluxes and on their temperature and light responses. Long-term measurements of BVOC are still lacking for nearly all ecosystems and only a very few studies about seasonal or even interannual variation of BVOC emissions have been published so far, particularly for northern ecosystems. The results presented here will be useful for testing process understanding obtained in laboratory studies and for model evaluation, improving our understanding of biogeochemical cycles in a region which is likely to be sensitive to climate change and currently undergoes rapid changes due to global warming.

POSSIBILITY OF HIGH-FREQUENCY OBSERVATION OF INUNDATION AREA BY SMALL SAR SATELLITES CONSTELLATION

2020 ◽  
Vol 76 (2) ◽  
pp. I_535-I_540
Author(s):  
Natsumi KITAJIMA ◽  
Rie SETO ◽  
Dai YAMAZAKI ◽  
Xudong ZHOU ◽  
Wenchao MA ◽  
...  
Keyword(s):  
High Frequency ◽  
Inundation Area ◽  
Frequency Observation

scholarly journals BVOC ecosystem flux measurements at a high latitude wetland site

2010 ◽  
Vol 10 (4) ◽  
pp. 1617-1634 ◽  
Author(s):  
T. Holst ◽  
A. Arneth ◽  
S. Hayward ◽  
A. Ekberg ◽  
M. Mastepanov ◽  
...  
Keyword(s):  
High Frequency ◽  
Boreal Forests ◽  
Sonic Anemometer ◽  
Proton Transfer Reaction ◽  
Heat Fluxes ◽  
Emission Rates ◽  
Water Vapour Concentration ◽  
Emission Fluxes ◽  
Flux Measurements ◽  
Ecosystem Flux

Abstract. In this study, we present summertime concentrations and fluxes of biogenic volatile organic compounds (BVOCs) measured at a sub-arctic wetland in northern Sweden using a disjunct eddy-covariance (DEC) technique based on a proton transfer reaction mass spectrometer (PTR-MS). The vegetation at the site was dominated by Sphagnum, Carex and \\textit{Eriophorum} spp. The measurements reported here cover a period of 50 days (1 August to 19 September 2006), approximately one half of the growing season at the site, and allowed to investigate the effect of day-to-day variation in weather as well as of vegetation senescence on daily BVOC fluxes, and on their temperature and light responses. The sensitivity drift of the DEC system was assessed by comparing H3O+-ion cluster formed with water molecules (H3O+(H2O) at m37) with water vapour concentration measurements made using an adjacent humidity sensor, and the applicability of the DEC method was analysed by a comparison of sensible heat fluxes for high frequency and DEC data obtained from the sonic anemometer. These analyses showed no significant PTR-MS sensor drift over a period of several weeks and only a small flux-loss due to high-frequency spectrum omissions. This loss was within the range expected from other studies and the theoretical considerations. Standardised (20 °C and 1000 μmol m−2 s−1 PAR) summer isoprene emission rates found in this study of 329 μg C m−2 (ground area) h−1 were comparable with findings from more southern boreal forests, and fen-like ecosystems. On a diel scale, measured fluxes indicated a stronger temperature dependence than emissions from temperate or (sub)tropical ecosystems. For the first time, to our knowledge, we report ecosystem methanol fluxes from a sub-arctic ecosystem. Maximum daytime emission fluxes were around 270 μg m−2 h−1 (ca. 100 μg C m−2 h−1), and during most nights small negative fluxes directed from the atmosphere to the surface were observed.

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