scholarly journals Are mean vertical velocities from PMSE a good representation of mean vertical winds?

2018 ◽  
Author(s):  
Nikoloz Gudadze ◽  
Gunter Stober ◽  
Jorge L. Chau
Keyword(s):  
Vertical Velocity ◽  
Middle Atmosphere ◽  
Weighted Average ◽  
Sharp Decrease ◽  
Good Representation ◽  
Velocity Measurements ◽  
Particle Sedimentation ◽  
Lower Upper ◽  
The Mean ◽  
Vertical Winds

Abstract. Mean vertical velocity measurements obtained from Radars at polar latitudes using Polar Mesosphere Summer Echoes (PMSE) as an inert tracer have been considered as non-representative of the mean vertical winds over the last couple of decades. PMSEs observed with the Middle Atmosphere Alomar Radar System (MAARSY) over Andøya, Norway (69.30° N, 16.04° E) during summers of 2016 and 2017 are used to derive mean vertical winds in the upper mesosphere. The 3D vector wind components (zonal, meridional and vertical) are based on a Doppler beam swinging experiment using 5-beam directions (one vertical and four obliques). The 3D wind components are computed using a recently developed wind retrieval technique. The method includes full non-linear error-propagation, spatial and temporal regularization as well as beam pointing corrections and angular pointing uncertainties. Measurement uncertainties are used as weights to obtain seasonal weighted averages and characterize seasonal mean vertical velocity. Weighted average values of vertical velocities reveal a weak upward behaviour at altitudes 84–87 km after eliminating the influence of ice falling speed. At the same time, a sharp decrease/increase in the mean vertical velocities at the lower/upper edges of the summer mean altitude profile prevails, which are attributed to the sampling issues of PMSE due to disappearing of the target corresponding to the certain regions of motions and temperatures. Thus the mean vertical velocities can be biased with decrease up-/down-ward velocity measurements at lower/upper edges, while at the main central region the obtained mean vertical velocities are consistent with expected values of mean vertical winds after considering ice particle sedimentation.

scholarly journals Can VHF radars at polar latitudes measure mean vertical winds in the presence of PMSE?

2019 ◽  
Vol 19 (7) ◽  
pp. 4485-4497 ◽  
Author(s):  
Nikoloz Gudadze ◽  
Gunter Stober ◽  
Jorge L. Chau
Keyword(s):  
Middle Atmosphere ◽  
Weighted Average ◽  
Sharp Decrease ◽  
Particle Sedimentation ◽  
Wind Retrieval ◽  
Retrieval Technique ◽  
Summer Echoes ◽  
Polar Mesosphere Summer Echoes ◽  
The Mean ◽  
Vertical Winds

Abstract. Mean vertical velocity measurements obtained from radars at polar latitudes using polar mesosphere summer echoes (PMSEs) as an inert tracer have been considered to be non-representative of the mean vertical winds over the last couple of decades. We used PMSEs observed with the Middle Atmosphere Alomar Radar System (MAARSY) over Andøya, Norway (69.30∘ N, 16.04∘ E), during summers of 2016 and 2017 to derive mean vertical winds in the upper mesosphere. The 3-D vector wind components (zonal, meridional and vertical) are based on a Doppler beam swinging experiment using five beam directions (one vertical and four oblique). The 3-D wind components are computed using a recently developed wind retrieval technique. The method includes full non-linear error propagation, spatial and temporal regularisation, and beam pointing corrections and angular pointing uncertainties. Measurement uncertainties are used as weights to obtain seasonal weighted averages and characterise seasonal mean vertical velocities. Weighted average values of vertical velocities reveal a weak upward behaviour at altitudes ∼84–87 km after eliminating the influence of the speed of falling ice. At the same time, a sharp decrease (increase) in the mean vertical velocities at the lower (upper) edges of the summer mean altitude profile, which are attributed to the sampling issues of the PMSE due to disappearance of the target corresponding to the certain regions of motions and temperatures, prevails. Thus the mean vertical velocities can be biased downwards at the lower edge, and the mean vertical velocities can be biased upwards at the upper edge, while at the main central region the obtained mean vertical velocities are consistent with expected upward values of mean vertical winds after considering ice particle sedimentation.

scholarly journals Vertical velocities associated with gravity waves measured in the mesosphere and lower thermosphere with the EISCAT VHF radar

1998 ◽  
Vol 16 (10) ◽  
pp. 1367-1379 ◽  
Author(s):  
N. J. Mitchell ◽  
V. St. C. Howells
Keyword(s):  
Gravity Waves ◽  
Vertical Velocity ◽  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Motion Field ◽  
Vhf Radar ◽  
Height Range ◽  
The Mean ◽  
Vertical Winds ◽  
Mean Variance

Abstract. The EISCAT VHF radar (69.4°N, 19.1°E) has been used to record vertical winds at mesopause heights on a total of 31 days between June 1990 and January 1993. The data reveal a motion field dominated by quasi-monochromatic gravity waves with representative apparent periods of ~30–40 min, amplitudes of up to ~2.5 m s–1 and large vertical wavelength. In some instances waves appear to be ducted. Vertical profiles of the vertical-velocity variance display a variety of forms, with little indication of systematic wave growth with height. Daily mean variance profiles evaluated for consecutive days of recording show that the general shape of the variance profiles persists over several days. The mean variance evaluated over a 10 km height range has values from 1.2 m2s–2 to 6.5 m2s–2 and suggests a semi-annual seasonal cycle with equinoctial minima and solsticial maxima. The mean vertical wavenumber spectrum evaluated at heights up to 86 km has a slope (spectral index) of –1.36 ± 0.2, consistent with observations at lower heights but disagreeing with the predictions of a number of saturation theories advanced to explain gravity-wave spectra. The spectral slopes evaluated for individual days have a range of values, and steeper slopes are observed in summer than in winter. The spectra also appear to be generally steeper on days with lower mean vertical-velocity variance.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides)

The intense vorticity structures near the turbulent/non-turbulent interface in a jet

2011 ◽  
Vol 685 ◽  
pp. 165-190 ◽  
Author(s):  
Carlos B. da Silva ◽  
Ricardo J. N. dos Reis ◽  
José C. F. Pereira
Keyword(s):  
Reynolds Number ◽  
Shear Layer ◽  
Isotropic Turbulence ◽  
Tangential Velocity ◽  
Sharp Decrease ◽  
Good Representation ◽  
Micro Scale ◽  
Vortex Model ◽  
Burgers Vortex ◽  
The Mean

AbstractThe characteristics of the intense vorticity structures (IVSs) near the turbulent/non-turbulent (T/NT) interface separating the turbulent and the irrotational flow regions are analysed using a direct numerical simulation (DNS) of a turbulent plane jet. The T/NT interface is defined by the radius of the large vorticity structures (LVSs) bordering the jet edge, while the IVSs arise only at a depth of about $5\eta $ from the T/NT interface, where $\eta $ is the Kolmogorov micro-scale. Deep inside the jet shear layer the characteristics of the IVSs are similar to the IVSs found in many other flows: the mean radius, tangential velocity and circulation Reynolds number are $R/ \eta \approx 4. 6$, ${u}_{0} / {u}^{\ensuremath{\prime} } \approx 0. 8$, and ${\mathit{Re}}_{\Gamma } / { \mathit{Re}}_{\lambda }^{1/ 2} \approx 28$, where ${u}_{0} $, and ${\mathit{Re}}_{\lambda } $ are the root mean square of the velocity fluctuations and the Reynolds number based on the Taylor micro-scale, respectively. Moreover, as in forced isotropic turbulence the IVSs inside the jet are well described by the Burgers vortex model, where the vortex core radius is stable due to a balance between the competing effects of axial vorticity production and viscous diffusion. Statistics conditioned on the distance from the T/NT interface are used to analyse the effect of the T/NT interface on the geometry and dynamics of the IVSs and show that the mean radius $R$, tangential velocity ${u}_{0} $ and circulation $\Gamma $ of the IVSs increase as the T/NT interface is approached, while the vorticity norm $\vert \omega \vert $ stays approximately constant. Specifically $R$, ${u}_{0} $ and $\Gamma $ exhibit maxima at a distance of roughly one Taylor micro-scale from the T/NT interface, before decreasing as the T/NT is approached. Analysis of the dynamics of the IVS shows that this is caused by a sharp decrease in the axial stretching rate acting on the axis of the IVSs near the jet edge. Unlike the IVSs deep inside the shear layer, there is a small predominance of vortex diffusion over stretching for the IVSs near the T/NT interface implying that the core of these structures is not stable i.e. it will tend to grow in time. Nevertheless the Burgers vortex model can still be considered to be a good representation for the IVSs near the jet edge, although it is not as accurate as for the IVSs deep inside the jet shear layer, since the observed magnitude of this imbalance is relatively small.

scholarly journals First observation of one noctilucent cloud by a twin lidar in two different directions

2002 ◽  
Vol 20 (11) ◽  
pp. 1863-1868 ◽  
Author(s):  
G. Baumgarten ◽  
F.-J. Lübken ◽  
K. H. Fricke
Keyword(s):  
Middle Atmosphere ◽  
Early Morning ◽  
Atmospheric Composition ◽  
Noctilucent Cloud ◽  
Particle Sedimentation ◽  
Composition And Structure ◽  
Cross Correlation Analysis ◽  
Wind Measurements ◽  
The Mean ◽  
Observation Period

Abstract. In the early morning hours of 14 July 1999, a noctilucent cloud (NLC) was observed simultaneously by the two branches of a twin lidar system located at the ALOMAR observatory in northern Norway (69° N). The telescopes of the two lidars were pointing vertical (L^) and off the zenith by 30° (L30°). The two lidars detected an enhancement in the altitude profile of backscattered light (relative to the molecular background) for more than 5 h, starting approximately at 01:00 UT. These measurements constitute the detection of one NLC by two lidars under different directions and allow for a detailed study of the morphology of the NLC layer. A cross-correlation analysis of the NLC signals demonstrates that the main structures seen by both lidars are practically identical. This implies that a temporal evolution of the microphysics within the NLC during its drift from one lidar beam to the other is negligible. From the time delay of the NLC structures, a drift velocity of 55–65 m/s is derived which agrees nicely with radar wind measurements. During the observation period, the mean NLC altitude decreases by ~0.5 km/h (=14 cm/s) at both observation volumes. Further-more, the NLC is consistently observed approximately 500 m lower in altitude at L30° compared to L^. Supplementing these data by observations from rocket-borne and ground-based instruments, we show that the general downward progression of the NLC layer through the night, as seen by both lidars, is caused by a combination of particle sedimentation by 4–5 cm/s and a downward directed vertical wind by 9–10 cm/s, whereas a tilt of the layer in drift direction can be excluded.Key words. Atmospheric composition and structure (cloud physics and chemistry; aerosols and particles) Meteorology and atmospheric dynamics (middle atmosphere dynamics)

scholarly journals Mucosa plication reinforced colorectal anastomosis and trans-anal vacuum drainage: a pilot study with preliminary results

2021 ◽  
Author(s):  
Alexander Ferko ◽  
Juraj Váňa ◽  
Marek Adámik ◽  
Adam Švec ◽  
Michal Žáček ◽  
...  
Keyword(s):  
Pilot Study ◽  
Povidone Iodine ◽  
Anal Verge ◽  
Colorectal Anastomosis ◽  
Stapled Anastomosis ◽  
Neoadjuvant Radiotherapy ◽  
Lower Upper ◽  
Registration Number ◽  
The Mean ◽  
Diversion Rate

AbstractDehiscence of colorectal anastomosis is a serious complication that is associated with increased mortality, impaired functional and oncological outcomes. The hypothesis was that anastomosis reinforcement and vacuum trans-anal drainage could eliminate some risk factors, such as mechanically stapled anastomosis instability and local infection. Patients with rectal cancer within 10 cm of the anal verge and low anterior resection with double-stapled technique were included consecutively. A stapler anastomosis was supplemented by trans-anal reinforcement and vacuum drainage using a povidone-iodine-soaked sponge. Modified reinforcement using a circular mucosa plication was developed and used. Patients were followed up by postoperative endoscopy and outcomes were acute leak rate, morbidity, and diversion rate. The procedure was successfully completed in 52 from 54 patients during time period January 2019–October 2020. The mean age of patients was 61 years (lower–upper quartiles 54–69 years). There were 38/52 (73%) males and 14/52 (27%) females; the neoadjuvant radiotherapy was indicated in a group of patients in 24/52 (46%). The mean level of anastomosis was 3.8 cm (lower–upper quartiles 3.00–4.88 cm). The overall morbidity was 32.6% (17/52) and Clavien–Dindo complications ≥ 3 grade appeared in 3/52 (5.7%) patients. No loss of anastomosis was recorded and no patient died postoperatively. The symptomatic anastomotic leak was recorded in 2 (3.8%) patients and asymptomatic blind fistula was recorded in one patient 1/52 (1.9%). Diversion ileostomy was created in 1/52 patient (1.9%). Reinforcement of double-stapled anastomosis using a circular mucosa plication with combination of vacuum povidone-iodine-soaked sponge drainage led to a low acute leak and diversion rate. This pilot study requires further investigation.Registered at ClinicalTrials.gov.: Trial registration number is NCT04735107, date of registration February 2, 2021, registered retrospectively.

scholarly journals Image Enhanced Mask R-CNN: A Deep Learning Pipeline with New Evaluation Measures for Wind Turbine Blade Defect Detection and Classification

2021 ◽  
Vol 7 (3) ◽  
pp. 46
Author(s):  
Jiajun Zhang ◽  
Georgina Cosma ◽  
Jason Watkins
Keyword(s):  
Deep Learning ◽  
Wind Turbine ◽  
Turbine Blade ◽  
Defect Detection ◽  
Recognition Rate ◽  
Weighted Average ◽  
Wind Turbine Blade ◽  
Evaluation Measures ◽  
Augmentation Techniques ◽  
The Mean

Demand for wind power has grown, and this has increased wind turbine blade (WTB) inspections and defect repairs. This paper empirically investigates the performance of state-of-the-art deep learning algorithms, namely, YOLOv3, YOLOv4, and Mask R-CNN for detecting and classifying defects by type. The paper proposes new performance evaluation measures suitable for defect detection tasks, and these are: Prediction Box Accuracy, Recognition Rate, and False Label Rate. Experiments were carried out using a dataset, provided by the industrial partner, that contains images from WTB inspections. Three variations of the dataset were constructed using different image augmentation settings. Results of the experiments revealed that on average, across all proposed evaluation measures, Mask R-CNN outperformed all other algorithms when transformation-based augmentations (i.e., rotation and flipping) were applied. In particular, when using the best dataset, the mean Weighted Average (mWA) values (i.e., mWA is the average of the proposed measures) achieved were: Mask R-CNN: 86.74%, YOLOv3: 70.08%, and YOLOv4: 78.28%. The paper also proposes a new defect detection pipeline, called Image Enhanced Mask R-CNN (IE Mask R-CNN), that includes the best combination of image enhancement and augmentation techniques for pre-processing the dataset, and a Mask R-CNN model tuned for the task of WTB defect detection and classification.

scholarly journals Observation of Kelvin–Helmholtz instabilities and gravity waves in the summer mesopause above Andenes in Northern Norway

2018 ◽  
Vol 18 (9) ◽  
pp. 6721-6732 ◽  
Author(s):  
Gunter Stober ◽  
Svenja Sommer ◽  
Carsten Schult ◽  
Ralph Latteck ◽  
Jorge L. Chau
Keyword(s):  
Gravity Waves ◽  
Middle Atmosphere ◽  
Phase Speed ◽  
Velocity Measurements ◽  
Wind Variability ◽  
Short Period ◽  
Strong Shear ◽  
Summer Echoes ◽  
Period Wave ◽  
Horizontal Wavelength

Abstract. We present observations obtained with the Middle Atmosphere Alomar Radar System (MAARSY) to investigate short-period wave-like features using polar mesospheric summer echoes (PMSEs) as a tracer for the neutral dynamics. We conducted a multibeam experiment including 67 different beam directions during a 9-day campaign in June 2013. We identified two Kelvin–Helmholtz instability (KHI) events from the signal morphology of PMSE. The MAARSY observations are complemented by collocated meteor radar wind data to determine the mesoscale gravity wave activity and the vertical structure of the wind field above the PMSE. The KHIs occurred in a strong shear flow with Richardson numbers Ri < 0.25. In addition, we observed 15 wave-like events in our MAARSY multibeam observations applying a sophisticated decomposition of the radial velocity measurements using volume velocity processing. We retrieved the horizontal wavelength, intrinsic frequency, propagation direction, and phase speed from the horizontally resolved wind variability for 15 events. These events showed horizontal wavelengths between 20 and 40 km, vertical wavelengths between 5 and 10 km, and rather high intrinsic phase speeds between 45 and 85 m s−1 with intrinsic periods of 5–10 min.

scholarly journals Features of the Spring Flood Formation in the Arpa River Basin

2021 ◽  
pp. 126-152
Author(s):  
Keyword(s):  
River Basin ◽  
Weighted Average ◽  
Close Correlation ◽  
Annual Runoff ◽  
Average Height ◽  
Spring Flood ◽  
Correlation Relationship ◽  
Catchment Areas ◽  
The Mean ◽  
Maximum Runoff

The article considers main physical and geographical factors affecting the runoff, spring flood of rivers in the Arpa River basin, and analyzes the regularities of their spacetime distribution. The authors have obtained correlation relationship between the values of the flood runoff layer, the mean module maximum runoff and weighted average height of the catchment area of the Arpa River, between the mean annual maximum runoff module for the period floods and catchment areas of rivers. These dependencies can be used for preliminary estimates of the spring flood runoff of unexplored rivers of the territory under consideration. A close correlation between the values of the annual runoff and the runoff of the spring flood in the section of the Arpa River – Dzhermuk has been also revealed. It can be used for forecasting the annual flow.

scholarly journals The influence of methods of basic tillage and fertilizers on the content of basic nutrients in leached chernozem

2022 ◽  
Vol 354 (11-12) ◽  
pp. 123-128
Author(s):  
E. V. Kuzina
Keyword(s):  
Spring Wheat ◽  
Nitrate Nitrogen ◽  
Weighted Average ◽  
Sharp Decrease ◽  
Economic Feasibility ◽  
Adaptive Landscape ◽  
Mineral Fertilizers ◽  
Industrial Complex ◽  
Biological Product ◽  
Resource Saving

Relevance. The preservation, reproduction and rational use of agricultural soil fertility is the main condition for the stable development of the agro-industrial complex. Mechanical tillage systems, the use of mineral and microbiological fertilizers are one of the main links in adaptive landscape farming systems. In the conditions of a sharp decrease in the rates of fertilizer application, an increase in the imbalance of elements of mineral nutrition of plants observed in recent years in agroecosystems, the function of improving the regimes of chernozems, preserving their fertility is designed to perform resource-saving technologies of soil cultivation in combination with effective methods of using agrochemicals that combine environmental and economic feasibility.Methods. The experiments were laid in 2017–2019 on chernozem heavy loamy soils typical for most farms in the Ulyanovsk region. The object of the study is spring wheat, the variety Ulyanovskaya 100. The subject of the study is the methods of tillage, doses of mineral fertilizers, the biological product "BisolbiFit". The following technological methods of using the biological product were studied: seed treatment before sowing, non-root treatment of vegetating plants and a combination of these methods. The experiment was carried out on three backgrounds: N0P0K0 (control); 2) N30P30K30; 3) N60P60K60.Results. It was found that the best nitrification ability was possessed by variants with fine combback and comb-back with soil-deepening treatment, in which the weighted average content of nitrate nitrogen was 3.29–3.33 mg/100 g, which is 35–36%; 26–28%; 43–44% more than with fine, conventional non-dump and dump treatment respectively. Plowing improved the conditions of phosphorus and potassium nutrition of plants by 25–37% and 6–14% compared to other treatments. When N30P30K30 and N60 P60 K60 were applied to the soil, the content of nitrate nitrogen increased by 46 and 91%, phosphorus — by 0–14% and potassium — by 6 and 21% compared to the nonfertilized background. More effective in terms of the effect on the productivity of spring wheat were comb-shaped treatments, where the average yield was 2.89–2.94 t/ha, which exceeded the usual plowing by 0.19–0.24 t/ha. The greatest increase in yield was obtained when combining the methodsseed treatment + spraying of vegetative plants with the biological preparation "BisolbiFit". On an unfertilized background, the increase in grain yield was -0.71, on the background of N30P30K30 — 1.04, on the background of N60P60K60 — 1.56 t/ha.

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