scholarly journals Validation of wind measurements of two MST radars in northern Sweden and in Antarctica

2020 ◽  
Author(s):  
Evgenia Belova ◽  
Peter Voelger ◽  
Sheila Kirkwood ◽  
Susanna Hagelin ◽  
Magnus Lindskog ◽  
...  
Keyword(s):  
Radar Data ◽  
Research Station ◽  
Random Errors ◽  
Meridional Component ◽  
Analysis Technique ◽  
Meridional Winds ◽  
Wind Measurements ◽  
The Mean ◽  
Mean Differences ◽  
Nwp Model

Abstract. Two atmospheric VHF radars: ESRAD located near Kiruna in the Swedish Artic and MARA at Indian research station Maitri in Antarctica perform wind measurements in the troposphere and lower stratosphere on a regular basis. We compared horizontal winds at altitudes between about 0.5 km and 14 km derived from the radar data using the full correlation analysis technique with radiosonde observations and models. The comparison with 28 radiosondes launched from January 2017 to August 2019 showed that ESRAD underestimates the zonal and meridional winds by about 8 % and 25 %, respectively. The mean differences between the radar and radiosonde winds are −1.4 m/s and 0.4 m/s. A similar result was found when comparing with the regional NWP model HARMONIE-AROME for the period September 2018–May 2019. The ESRAD random error was estimated to be 2.8 m/s (2.4 m/s) for the zonal (meridional) component. The comparison of MARA with the ECMWF ERA5 reanalysis for January–December 2019 reveals good agreement between them with the mean difference between 0.1 m/s and −0.5 m/s depending on the component and season. The MARA random errors are 2.6 m/s and 2.3 m/s for the zonal and meridional winds, respectively.

scholarly journals Validation of wind measurements of two mesosphere–stratosphere–troposphere radars in northern Sweden and in Antarctica

2021 ◽  
Vol 14 (4) ◽  
pp. 2813-2825
Author(s):  
Evgenia Belova ◽  
Peter Voelger ◽  
Sheila Kirkwood ◽  
Susanna Hagelin ◽  
Magnus Lindskog ◽  
...  
Keyword(s):  
Weather Prediction ◽  
Radar Data ◽  
Numerical Weather Prediction Model ◽  
Mean Difference ◽  
Research Station ◽  
Random Errors ◽  
Meridional Winds ◽  
Wind Measurements ◽  
The Mean ◽  
High Level

Abstract. Two atmospheric VHF radars: ESRAD (Esrange MST radar) located near Kiruna in the Swedish Arctic and MARA (Moveable Atmospheric Radar for Antarctica) at the Indian research station Maitri in Antarctica perform wind measurements in the troposphere and lower stratosphere on a regular basis. We compared horizontal winds at altitudes between about 0.5 and 14 km derived from the radar data using the full correlation analysis (FCA) technique with radiosonde observations and models. The comparison with 28 radiosondes launched from January 2017 to August 2019 showed that ESRAD underestimates the zonal and meridional winds by about 8 % and 25 %, respectively. This is likely caused by the receiver group arrangement used for the FCA together with a high level of non-white noise. A similar result was found when comparing with the regional numerical weather prediction model HARMONIE-AROME (Bengtsson et al., 2017) for the period September 2018–May 2019. The MARA winds were compared with winds from radiosondes for the period February–October 2014 (291 occasions). In contrast to ESRAD, there is no indication that MARA underestimates the winds compared to the sondes. The mean difference between the radar and radiosonde winds is close to zero for both zonal and meridional components. The comparison of MARA with the ECMWF ERA5 reanalysis for January–December 2019 reveals good agreement with the mean difference between 0.1 and −0.5 m/s depending on the component and season. The random errors in the wind components (standard deviations over all estimates in 1 h averages) are typically 2–3 m/s for both radars. Standard deviation of the differences between radars and sondes are 3–5 m/s.

scholarly journals Simultaneous and co-located wind measurements in the middle atmosphere by lidar and rocket-borne techniques

2016 ◽  
Vol 9 (8) ◽  
pp. 3911-3919 ◽  
Author(s):  
Franz-Josef Lübken ◽  
Gerd Baumgarten ◽  
Jens Hildebrand ◽  
Francis J. Schmidlin
Keyword(s):  
Middle Atmosphere ◽  
Systematic Difference ◽  
Horizontal Distance ◽  
In Situ Method ◽  
Time Period ◽  
Meridional Winds ◽  
Wind Measurements ◽  
In Situ Observations ◽  
Mean Differences

Abstract. We present the first comparison of a new lidar technique to measure winds in the middle atmosphere, called DoRIS (Doppler Rayleigh Iodine Spectrometer), with a rocket-borne in situ method, which relies on measuring the horizontal drift of a target (“starute”) by a tracking radar. The launches took place from the Andøya Space Center (ASC), very close to the ALOMAR observatory (Arctic Lidar Observatory for Middle Atmosphere Research) at 69° N. DoRIS is part of a steerable twin lidar system installed at ALOMAR. The observations were made simultaneously and with a horizontal distance between the two lidar beams and the starute trajectories of typically 0–40 km only. DoRIS measured winds from 14 March 2015, 17:00 UTC, to 15 March 2015, 11:30 UTC. A total of eight starute flights were launched successfully from 14 March, 19:00 UTC, to 15 March, 00:19 UTC. In general there is excellent agreement between DoRIS and the in situ measurements, considering the combined range of uncertainties. This concerns not only the general height structures of zonal and meridional winds and their temporal developments, but also some wavy structures. Considering the comparison between all starute flights and all DoRIS observations in a time period of ±20 min around each individual starute flight, we arrive at mean differences of typically ±5–10 m s−1 for both wind components. Part of the remaining differences are most likely due to the detection of different wave fronts of gravity waves. There is no systematic difference between DoRIS and the in situ observations above 30 km. Below ∼ 30 km, winds from DoRIS are systematically too large by up to 10–20 m s−1, which can be explained by the presence of aerosols. This is proven by deriving the backscatter ratios at two different wavelengths. These ratios are larger than unity, which is an indication of the presence of aerosols.

Field campaign for the comparison of SOUSY radar wind measurements with rawinsonde and model data

1994 ◽  
Vol 12 (8) ◽  
pp. 746-764 ◽  
Author(s):  
H. Steinhagen ◽  
A. Christoph ◽  
P. Czechowsky ◽  
U. Görsdorf ◽  
M. Gube-Lenhardt ◽  
...  
Keyword(s):  
Numerical Algorithms ◽  
Radar Data ◽  
Wind Profiler ◽  
Random Errors ◽  
Vhf Radar ◽  
Field Campaign ◽  
Forecast Models ◽  
Wind Measurements ◽  
Wind Profiles ◽  
Estimation Of Variance

Abstract. A field campaign was carried out from 26 October to 7 November 1992, using the SOUSY-VHF radar and a mobile rawinsonde system installed and operated nearby to produce vertical wind profiles. The purpose of this campaign was to compare the two types of wind measurements with one another and with results from forecast models. Numerical algorithms were developed and applied to the radar data in order to eliminate random errors, correct for velocity aliasing, and calculate the effective zenith angle of the off-vertical beams. Differences between wind profiler data and rawinsonde or model results depend not only upon the errors of the different systems, but also on temporal and spatial variations of the wind field. Therefore, methods for the comparison of radar and rawinsonde data were developed which take into consideration these variations. The practical potential of these methods is demonstrated by comparisons of rawinsonde and radar wind profiles. The comparison of radar data and model output shows excellent agreement in the direction and in the speed of the wind at virtually all altitudes. An evaluation of the quality of wind profiler measurements is possible using the estimation of variance and variability of wind components.

scholarly journals MF radar observations of mean winds and tides over Poker Flat, Alaska (65.1° N, 147.5° W)

2002 ◽  
Vol 20 (5) ◽  
pp. 679-690 ◽  
Author(s):  
P. Kishore ◽  
S. P. Namboothiri ◽  
K. Igarashi ◽  
Y. Murayama ◽  
B. J. Watkins
Keyword(s):  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Winter Season ◽  
Wave Model ◽  
Global Scale ◽  
Meridional Winds ◽  
Wind Measurements ◽  
The Mean ◽  
Tidal Characteristics ◽  
Mf Radar

Abstract. MF radar wind measurements in the mesosphere and lower thermosphere over Poker Flat, Alaska (65.1° N, 147.5° W) are used to study the features of mean winds and solar tides. Continuous observation with the newly installed radar is in progress and in the present study we have analyzed a database of the first 27 months (October 1998–December 2000) of observation. The observed mean wind climatology has been compared with previous measurements and the latest empirical model values (HWM93 model). Similarly, the tidal characteristics are described and compared with the Global Scale Wave Model (GSWM00). The mean wind characteristics observed are fairly consistent with previous wind measurements by the Poker Flat MST radar. The main feature of the zonal circulation is the annual variation with summer westward flow and winter eastward flow. The annual mean zonal wind has a west-ward motion at altitudes below 90 km. The annual mean meridional circulation has mainly southward motion at 70–100 km. There is very good agreement between the radar zonal winds and the HWM93 model winds. Comparison of the meridional winds shows some discrepancy. Analysis of two years of data indicated that the year-to-year consistency is preserved in the mean circulation in the mesosphere. Tidal characteristics observed are also consistent with previous measurements. Semidiurnal tides have the largest amplitudes in summer while the weakest amplitude is observed during the winter months. The vertical wavelength is longer during the summer season compared to the winter season. Comparison with the GSWM00 produces mixed results. There is reasonable agreement between the observed and modeled phases. Diurnal tide amplitudes are comparable in magnitude with that of the semidiurnal tide. Seasonal variation is less evident in the amplitudes. Comparison of the observed tidal parameters with the GSWM00 reveals some agreement and discrepancies.Key words. Meteorology and atmospheric dynamics (climatology; middle atmosphere dynamics; waves and tides)

scholarly journals Measurement of momentum flux using two meteor radars in Indonesia

2016 ◽  
Vol 34 (3) ◽  
pp. 369-377 ◽  
Author(s):  
Naoki Matsumoto ◽  
Atsuki Shinbori ◽  
Dennis M. Riggin ◽  
Toshitaka Tsuda
Keyword(s):  
Momentum Flux ◽  
Radar Data ◽  
Meteor Radar ◽  
Acquisition Rate ◽  
Annual Cycles ◽  
West Papua ◽  
Meridional Winds ◽  
West Sumatra ◽  
The Mean

Abstract. Two nearly identical meteor radars were operated at Koto Tabang (0.20° S, 100.32° E), West Sumatra, and Biak (1.17° S, 136.10° E), West Papua, in Indonesia, separated by approximately 4000 km in longitude on the Equator. The zonal and meridional momentum flux, u′w′ and v′w′, where u, v, and w are the eastward, northward, and vertical wind velocity components, respectively, were estimated at 86 to 94 km altitudes using the meteor radar data by applying a method proposed by Hocking (2005). The observed u′w′ at the two sites agreed reasonably well at 86, 90, and 94 km during the observation periods when the data acquisition rate was sufficiently large enough. Variations in v′w′ were consistent between 86, 90, and 94 km altitudes at both sites. The climatological variation in the monthly averaged u′w′ and v′w′ was investigated using the long-term radar data at Koto Tabang from November 2002 to November 2013. The seasonal variations in u′w′ and v′w′ showed a repeatable semiannual and annual cycles, respectively. u′w′ showed eastward values in February–April and July–September and v′w′ was northward in June to August at 90–94 km, both of which were generally anti-phase with the mean zonal and meridional winds, having the same periodicity. Our results suggest the usefulness of the Hocking method.

scholarly journals Simultaneous and co-located wind measurements in the middle atmosphere by lidar and rocket-borne techniques

2016 ◽  
Author(s):  
Franz-Josef Lübken ◽  
Gerd Baumgarten ◽  
Jens Hildebrand ◽  
Francis J. Schmidlin
Keyword(s):  
Gravity Waves ◽  
Middle Atmosphere ◽  
Systematic Difference ◽  
Horizontal Distance ◽  
Lidar System ◽  
Time Period ◽  
Meridional Winds ◽  
Wind Measurements ◽  
Mean Differences ◽  
Tracking Radar

Abstract. We present the first comparison of a new lidar technique to measure winds in the middle atmosphere, called DoRIS (Doppler Rayleigh Iodine Spectrometer), with rocket-borne insitu observations which rely on measuring the horizontal drift of a target ('starute') by a tracking radar. The launches took place from the Andøya Space Center (ASC), very close to the ALOMAR observatory (Arctic Lidar Observatory for Middle Atmosphere Research) at 69° N. DoRIS is part of a steerable twin lidar system installed at ALOMAR. The observations were made simultaneously and with a horizontal distance between the two lidar beams and the starute trajectories of typically 0–40 km only. DoRIS measured winds from 14 March 2015, 17:00 UTC to 15 March 2015, 11:30 UTC. A total of 8 starute flights were launched successfully from 14 March, 19:00 UTC to 15 March, 00:19 UTC. In general there is excellent agreement between DoRIS and the insitu measurements considering the combined range of uncertainties. This concerns not only the general height structures of zonal and meridional winds and their temporal developments, but also some wavy structures. Considering the comparison between all starute flights and all DoRIS observations in a time period of ±20 min around each individual starute flight, we arrive at mean differences of typically ±5–10 m/s for both wind components. Part of the remaining differences are most likely due to the detection of different wave fronts of gravity waves. There is no systematic difference between DoRIS and the insitu observations above 30 km. Below ~30 km winds from DoRIS are systematically too large by up to 10–20 m/s which can be explained by the presence of aerosols. This is proven by deriving the backscatter ratios at two different wavelengths. These ratios are larger than unity, which is an indication for the presence of aerosols.

scholarly journals Effectiveness of Home-Based Occupational Therapy on COPM Performance and Satisfaction Scores in Patients with COPD

2020 ◽  
pp. 000841742097112
Author(s):  
Eleonore H. Koolen ◽  
Martijn A. Spruit ◽  
Marianne de Man ◽  
Jeanine C. Antons ◽  
Elieke Nijhuis ◽  
...  
Keyword(s):  
Occupational Therapy ◽  
Integrated Management ◽  
Performance Measure ◽  
Occupational Performance ◽  
Post Intervention ◽  
Canadian Occupational Performance Measure ◽  
Home Based ◽  
Copd Patients ◽  
The Mean ◽  
Mean Differences

Background. Occupational therapy (OT) may be an important intervention in patients with COPD, but studies show conflicting results. Purpose. To evaluate the effectiveness of home-based monodisciplinary OT in COPD patients Method. We conducted an observational clinical study. Main outcomes were the mean differences in the Canadian Occupational Performance Measure (COPM) performance and satisfaction scores, pre and post intervention. Findings. Pre- and postintervention data were obtained from 41 patients. Statistically significant increases were observed in COPM performance (5.0 ± 1.1 versus 6.9 ± 0.9; P<0.001) and satisfaction (4.6 ± 1.3 versus 6.9 ± 1.0; P<0.001). The most frequently reported occupational performance problems were found in the domains of productivity (47%) and mobility (40%), fewer in self-care (10%) and the least in leisure (3%). Implications. Home-based monodisciplinary OT can contribute significantly to the improvement of daily functioning of patients with COPD. OT should therefore be considered more often as part of the integrated management of these patients.

scholarly journals The reproducibility of subjective appetite scores

1995 ◽  
Vol 73 (4) ◽  
pp. 517-530 ◽  
Author(s):  
Anne Raben ◽  
ANNA TAGLIABUE ◽  
Arne Astrup
Keyword(s):  
Visual Analogue Scale ◽  
Food Consumption ◽  
Analogue Scale ◽  
Prior Experience ◽  
Random Noise ◽  
Normal Weight ◽  
Vas Scores ◽  
The Mean ◽  
The Difference ◽  
Mean Differences

Although subjective appetite scores are widely used, studies on the reproducibility of this method are scarce. In the present study nine healthy, normal weight, young men recorded their subjective appetite sensations before and during 5 h after two different test meals A and B. The subjects tested each meal twice and in randomized order. Visual analogue scale (VAS) scores, 10 cm in length, were used to assess hunger, satiety, fullness, prospective food consumption and palatability of the meals. Plasma glucose and lactate concentrations were determined concomitantly. The repeatability was investigated for fasting values, Δ-mean 5 h and mean 5 h values, Δ-peak/nadir and peak/nadir values. Although the profiles of the postprandial responses were similar, the coefficients of repeatability (CR = 2SD) on the mean differences were large, ranging from 2·86 to 5.24 cm for fasting scores, 1·36 to 1·88 cm for mean scores, 2·98 to 5·42 cm for Δ-mean scores, and 3·16 to 6·44 cm for peak and Δ-peak scores. For palatability ratings the CK values varied more, ranging from 2·38 (taste) to 8·70 cm (aftertaste). Part of the difference in satiety ratings could be explained by the differences in palatability ratings. However, the low reproducibility may also be caused by a conditioned satiation or hunger due to the subjects' prior experience of the meals and therefore not just be a reflection of random noise. It is likely, however, that the variation in appetite ratings is due both to methodological day-to-day variation and to biological day-to-day variation in subjective appetite sensations.

Establishing inherent uncertainty in the shifts determined by volumetric imaging

2017 ◽  
Vol 16 (3) ◽  
pp. 258-264
Author(s):  
Upendra Kumar Giri ◽  
Anirudh Pradhan
Keyword(s):  
Linear Accelerator ◽  
Systematic Errors ◽  
Cone Beam ◽  
Random Errors ◽  
Mean Values ◽  
Volumetric Imaging ◽  
X Ray ◽  
Image Quality Control ◽  
The Mean ◽  
Six Degree Of Freedom

AbstractObjectiveThis study was conducted for establishing inherent uncertainty in the shift determination by X-ray volumetric imaging (XVI) and calculating margins due to this inherent uncertainty using van Herk formula.Material and methodsThe study was performed on the XVI which was cone-beam computed tomography integrated with the Elekta AxesseTM linear accelerator machine having six degree of freedom enabled HexaPOD couch. Penta-Guide phantom was used for inherent translational and rotational shift determination by repeated imaging. The process was repeated 20 times a day without moving the phantom for 30 consecutive working days. The measured shifts were used for margins calculation using van Herk formula.ResultsThe mean standard deviations were calculated as 0·05, 0·05, 0·06 mm in the three translational (x, y and z) and 0·05°, 0·05°, 0·05° in the three rotational axes (about x, y, z). Paired sample t-test was performed between the mean values of translational shifts (x, y, z) and rotational shifts. The systematic errors were found to be 0·03, 0·04 and 0·03 mm while the random errors were 0·05, 0·06 and 0·06 mm in the lateral, cranio-caudal and anterio-posterior directions, respectively. For the rotational shifts, the systematic errors were 0·02, 0·03 and 0·03 and the random errors were 0·06, 0·05 and 0·05 in the pitch, roll and yaw directions, respectively.ConclusionOur study concluded that there was an inherent uncertainty associated with the XVI tools, on the basis of these six-dimensional shifts, margins were calculated and recorded as a baseline for the quality assurance (QA) programme for XVI imaging tools by checking its reproducibility once in a year or after any major maintenance in hardware or upgradation in software. Although the shift determined was of the order of submillimetre order, still that shift had great significance for the image quality control of the XVI tools. Every departments practicing quality radiotherapy with such imaging tools should establish their own baseline value of inherent shifts and margins during the commissioning and must use an important QA protocol for the tools.

scholarly journals On the Convective Coupling and Moisture Organization of East Pacific Easterly Waves

2015 ◽  
Vol 72 (10) ◽  
pp. 3850-3870 ◽  
Author(s):  
Adam V. Rydbeck ◽  
Eric D. Maloney
Keyword(s):  
Life Cycle ◽  
Zonal Wind ◽  
Wind Shear ◽  
Warm Pool ◽  
Moisture Gradient ◽  
Easterly Waves ◽  
East Pacific ◽  
Pacific Warm Pool ◽  
Meridional Winds ◽  
The Mean

Abstract Processes associated with the local amplification of easterly waves (EWs) in the east Pacific warm pool are explored. Developing EWs favor convection in the southwest and northeast quadrants of the disturbance. In nascent EWs, convection favors the southwest quadrant. As the EW life cycle progresses, convection in the northeast quadrant becomes increasingly prominent and southwest quadrant convection wanes. The EW moisture budget reveals that anomalous meridional winds acting on the mean meridional moisture gradient of the ITCZ produce moisture anomalies supportive of convection in the southwest quadrant early in the EW life cycle. As EWs mature, moisture anomalies on the poleward side of the EW begin to grow and are supported by the advection of anomalous moisture by the mean zonal wind. In the southwest and northeast portions of the wave, where convection anomalies are favored, lower-tropospheric vorticity is generated locally through vertical stretching that supports a horizontal tilt of the wave from the southwest to the northeast. EWs with such tilts are then able to draw energy via barotropic conversion from the background cyclonic zonal wind shear present in the east Pacific. Convection anomalies associated with EWs vary strongly with changes in the background intraseasonal state. EWs during westerly and neutral intraseasonal periods are associated with robust convection anomalies. Easterly intraseasonal periods are, at times, associated with very weak EW convection anomalies because of weaker moisture and diluted CAPE variations.

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