Horizontal wind model (HWM) (1990)

1992 ◽  
Vol 40 (4) ◽  
pp. 556-557 ◽  
Author(s):  
A.E. Hedin
Keyword(s):  
Horizontal Wind ◽  
Wind Model

scholarly journals Monitoring observations of meteor echo at the EKB ISTP SB RAS radar: algorithms, validation, statistics

2021 ◽  
Vol 7 (1) ◽  
pp. 47-58
Author(s):  
Roman Fedorov ◽  
Oleg Berngardt
Keyword(s):  
Least Squares Method ◽  
Weighted Least Squares ◽  
Three Dimensional ◽  
Radar Data ◽  
Meteor Shower ◽  
Horizontal Wind ◽  
Doppler Velocity ◽  
Wind Model ◽  
Weighted Least Squares Method ◽  
Meteor Trails

The paper considers the implementation of algorithms for automatic search for signals scattered by meteor trails according to EKB ISTP SB RAS radar data. In general, the algorithm is similar to the algorithms adopted in specialized meteor systems. The algorithm is divided into two stages: detecting a meteor echo and determining its parameters. We show that on the day of the maximum Geminid shower, December 13, 2016, the scattered signals detected by the algorithm are foreshortening and correspond to scattering by irregularities extended in the direction of the meteor shower radiant. This confirms that the source of the signals detected by the algorithm is meteor trails. We implement an additional program for indirect trail height determination. It uses a decay time of echo and the NRLMSIS-00 atmosphere model to estimate the trail height. The dataset from 2017 to 2019 is used for further testing of the algorithm. We demonstrate a correlation in calculated Doppler velocity between the new algorithm and FitACF. We present a solution of the inverse problem of reconstructing the neutral wind velocity vector from the data obtained by the weighted least squares method. We compare calculated speeds and directions of horizontal neutral winds, obtained in the three-dimensional wind model, and the HWM-14 horizontal wind model. The algorithm allows real-time scattered signal processing and has been put into continuous operation at the EKB ISTP SB RAS radar.

scholarly journals Winds and tides in the mid-latitude Southern Hemisphere upper mesosphere recorded with the Falkland Islands SuperDARN radar

2011 ◽  
Vol 29 (11) ◽  
pp. 1985-1996 ◽  
Author(s):  
R. E. Hibbins ◽  
M. P. Freeman ◽  
S. E. Milan ◽  
J. M. Ruohoniemi
Keyword(s):  
Southern Hemisphere ◽  
Wind Data ◽  
Atmospheric Tides ◽  
Horizontal Wind ◽  
Falkland Islands ◽  
First Year ◽  
Wind Model ◽  
The North ◽  
Winter Time ◽  
Good Agreement

Abstract. Meteor wind data from the first year of operation of the Falkland Islands SuperDARN radar (52° S, 59° W) are used to characterize the atmospheric tides and background winds in the upper mesosphere above the South Atlantic. Strong (>40 m s−1) semidiurnal tides are observed in the winter time and large amplitude (>60 m s−1) bursts of quasi two-day wave activity are seen in January 2011. Data are in good agreement with those presented from the SAAMER meteor radar (54° S, 68° W). Comparison with SuperDARN meteor wind data from a geographically similar Northern Hemisphere site at Goose Bay (53° N 60° W) reveal clear interhemispheric differences especially in the semidiurnal and terdiurnal components of the tides. The winter time amplitudes of the tides are much stronger in the Southern Hemisphere than in the north. Background winds are observed to be significantly more polewards and westwards throughout the year than those predicted by the empirical horizontal wind model HWM07.

scholarly journals An update to the Horizontal Wind Model (HWM): The quiet time thermosphere

2015 ◽  
Vol 2 (7) ◽  
pp. 301-319 ◽  
Author(s):  
Douglas P. Drob ◽  
John T. Emmert ◽  
John W. Meriwether ◽  
Jonathan J. Makela ◽  
Eelco Doornbos ◽  
...  
Keyword(s):  
Horizontal Wind ◽  
Quiet Time ◽  
Wind Model

scholarly journals Modelo Semi-Empírico Médio Longitudinal de Ventos Termosféricos a 250 km para Períodos de Baixa Atividade Solar e Geomagnética

2020 ◽  
Vol 13 (4) ◽  
pp. 1442
Author(s):  
Wivaldo Dantas de Asevedo Júnior ◽  
Christiano Garnett Marques Brum ◽  
José Henrique Fernandez ◽  
Anderson Guimarães Guedes
Keyword(s):  
Statistical Tests ◽  
Computational Simulation ◽  
Upper Atmosphere ◽  
Horizontal Wind ◽  
Neutral Wind ◽  
Quiet Time ◽  
Wind Model ◽  
Seasonal Behavior ◽  
Semi Empirical

Neste trabalho é apresentado um modelo semi-empírico de ventos neutros termosféricos médios longitudinais para períodos de baixas atividades solar e geomagnética com dependência em hora local, dia do ano e latitude geográfica para 250 km de altitude. O modelo é denominado de SEATWIM (sigla em inglês para Semi Empirical Averaged Termospheric Wind Model) válido para períodos de baixa atividade solar e geomagnética. O SEATWIM foi construído a partir de uma análise estatística dos dados observados in situ obtidos pelo satélite UARS (Upper Atmosphere Research Satllite) por meio da carga útil WINDII (Wind Imaging Interferometer), onde os valores representativos para 250 km são obtidos pela média integrada em altitude entre 205 km e 275 km, e, a partir de uma análise estatístico-espectral, foi extraído comportamento diário e sazonal distribuídos em latitude geográfica. O modelo proposto exibe uma boa concordância em relação à climatologia dos dados observados pelo satélite para as componentes zonal e meridional dos ventos neutros termosférico em distintos períodos. Quando comparado ao comportamento dos dados observados, os índices estatísticos exibiram bons resultados, sendo os melhores resultados obtidos nos períodos de equinócio em ambas as componentes do vento termosférico. A validação estatística também exibiu melhores resultados para a componente zonal em comparação a componente meridional, para todos os períodos do ano. Os testes estatísticos utilizados indicam que o modelo SEATWIM assemelha-se ao modelo HWM14 (Horizontal Wind Model, versão 2014) principalmente em relação a componente zonal. Semi Empirical Longitudinal Averaged Termospheric Wind Model at 250 km for Solar and Geomagnectic Activities Quiet Time A B S T R A C TThis paper presents a semi empirical model of averaged longitudinal thermospheric neutral wind for quiet time periods of solar and geomagnetic activities with dependence on local time, day of the year and geographical latitude for 250 km of altitude, which was called SEATWIM (Semi Empirical Averaged Thermospheric Winds Model, the letter Q means quiet time of solar and magnectic activities). The SEATWIM was constructed from a statistical analysis of the observed in situ data obtained by the UARS satellite (Upper Atmosphere Research Satllite) through the WINDII payload equipment, where the representative values for 250 km are obtained by the average value integrated in altitude between 205 km and 275 km, and, from a statistical and spectral analysis, we extracted daily and seasonal behavior distributed over geographic latitude. The proposed model shows a good agreement with the climatology of the data observed by the satellite for the thermospheric neutral wind zonal and meridional directions. The statistical indices showed good results when compared to the behavior of the observed data being the best results obtained in the equinox periods in both thermospheric wind directions. Statistical validation also showed better results for the zonal component in comparison with the meridional component for all periods of the year. Statistical tests also indicate that the SEATWIM is similar to the HWM14 (Horizontal Wind Model, version 2014), mainly in the zonal direction.key-words: Computational simulation, termospheric neutral wind, SEATWIM

scholarly journals Observations of equatorial mesospheric winds over Cariri (7.4° S) by a meteor radar and comparison with existing models

2008 ◽  
Vol 26 (3) ◽  
pp. 485-497 ◽  
Author(s):  
R. A. Buriti ◽  
W. K. Hocking ◽  
P. P. Batista ◽  
A. F. Medeiros ◽  
B. R. Clemesha
Keyword(s):  
Annual Variation ◽  
Meridional Wind ◽  
The Other ◽  
Horizontal Wind ◽  
Meteor Radar ◽  
Wind Model ◽  
International Reference ◽  
Reference Atmosphere ◽  
One Year ◽  
Semiannual Oscillation

Abstract. Mesospheric winds observed with a meteor radar at Cariri (7.4° S, 36.5° W), Brazil, during the period of July 2004 to June 2005, show a clear semiannual oscillation known as the Mesospheric Semiannual Oscillation (MSAO), which maximizes in the zonal mean wind mainly at 82 km, with amplitude decreasing with height. Maximum westward winds for the MSAO occurred in March and September. The meridional wind, on the other hand, presented a clear annual variation maximizing in December. On average, the amplitude of the meridional MSAO was smaller than the zonal MSAO component. Comparison with models shows on occasions that there are significant differences between the observed winds and the CIRA (Cospar International Reference Atmosphere) and HWM93 (Horizontal Wind Model) models. In addition, diurnal and semidiurnal parameters were calculated and compared to the GSWM model. Other results observed during one year of data are presented in this work.

scholarly journals A Comparison of Meteor Radar Observation over China Region with Horizontal Wind Model (HWM14)

Atmosphere ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 98
Author(s):  
Qiong Tang ◽  
Yufeng Zhou ◽  
Zhitao Du ◽  
Chen Zhou ◽  
Jiandong Qiao ◽  
...  
Keyword(s):  
Model Prediction ◽  
Meridional Wind ◽  
Radar Observation ◽  
Horizontal Wind ◽  
Meteor Radar ◽  
Wind Fields ◽  
Wind Model ◽  
Zonal Winds ◽  
Radar Measurements ◽  
China Region

This paper compares the wind fields measured by the meteor radar at Mohe, Beijing, Wuhan, and Sanya stations and horizontal wind model (HWM14) predictions. HWM14 appears to successfully reproduce the height-time distribution of the monthly mean zonal winds, although large discrepancies occur in wind speed between the model and measurement, especially in the summer and winter months. For meridional wind, the consistency between model prediction and radar observation is worse than that of zonal wind. The consistency between radar measurements and model prediction at Sanya station is worse than other sites located at higher latitudes. Harmonic analysis reveals large discrepancies in diurnal, semidiurnal, and terdiurnal tides extracted from meteor radar observations and HWM14 predictions.

scholarly journals Climatology of thermospheric neutral winds over Oukaïmeden Observatory in Morocco

2017 ◽  
Vol 35 (1) ◽  
pp. 161-170 ◽  
Author(s):  
Mohamed Kaab ◽  
Zouhair Benkhaldoun ◽  
Daniel J. Fisher ◽  
Brian Harding ◽  
Aziza Bounhir ◽  
...  
Keyword(s):  
Dissociative Recombination ◽  
Horizontal Wind ◽  
Wind Model ◽  
Neutral Winds ◽  
Zonal Winds ◽  
Early Evening ◽  
Atlas Mountains ◽  
Fabry Perot ◽  
Meridional Winds ◽  
High Atlas Mountains

Abstract. In order to explore coupling between the thermosphere and ionosphere and to address the lack of data relating to thermospheric neutral winds and temperatures over the African sector, a new system of instruments was installed at the Oukaïmeden Observatory located in the high Atlas Mountains, 75 km south of Marrakesh, Morocco (31.206° N, 7.866° W, 22.84° N magnetic). In this work we present the first multi-year results of the climatology of meridional and zonal winds obtained during the period from January 2014 to February 2016, including observations from 648 nights. The measurements are obtained using an imaging Fabry–Pérot interferometer, which measures the 630.0 nm emissions caused by dissociative recombination of O2+. The basic climatology of the winds is as expected, showing zonal winds that are strongly eastward in the early evening just after sunset with a speed of 50 to 100 m s−1 decreasing in magnitude, and reversing directions in the local summer months, towards sunrise. The meridional winds are slightly poleward in the early evening during the local winter, before reversing directions around 21:00 LT. In the local summer months, the meridional winds are equatorward for the entire night, reaching a maximum equatorward speed of 75 m s−1. We compare the observed climatologies of neutral winds to that provided by the recently updated Horizontal Wind Model (HWM14) in order to validate that model's predictions of the thermospheric wind patterns over the eastern portion of Africa. The model captures much of the features in the observational climatologies. The most notable exception is for the zonal winds during local summer, when the maximum eastward wind in the observations occurs approximately 4 h later than seen in the model results.

scholarly journals Comparison of high-latitude thermospheric meridionalwinds I: optical and radar experimental comparisons

2004 ◽  
Vol 22 (3) ◽  
pp. 849-862 ◽  
Author(s):  
E. M. Griffin ◽  
I. C. F. Müller-Wodarg ◽  
A. Aruliah ◽  
A. Aylward
Keyword(s):  
Solar Cycle ◽  
High Latitude ◽  
Model Performance ◽  
Meridional Wind ◽  
Experimental Techniques ◽  
Horizontal Wind ◽  
Wind Model ◽  
Data Set ◽  
Neutral Winds ◽  
Eiscat Measurements

Abstract. Thermospheric neutral winds at Kiruna, Sweden (67.4°N, 20.4°E) are compared using both direct optical Fabry-Perot Interferometer (FPI) measurements and those derived from European incoherent scatter radar (EISCAT) measurements. This combination of experimental data sets, both covering well over a solar cycle of data, allows for a unique comparison of the thermospheric meridional component of the neutral wind as observed by different experimental techniques. Uniquely in this study the EISCAT measurements are used to provide winds for comparison using two separate techniques: the most popular method based on the work of Salah and Holt (1974) and the Meridional Wind Model (MWM) (Miller et al., 1997) application of servo theory. The balance of forces at this location that produces the observed diurnal pattern are investigated using output from the Coupled Thermosphere and Ionosphere (CTIM) numerical model. Along with detailed comparisons from short periods the climatological behaviour of the winds have been investigated for seasonal and solar cycle dependence using the experimental techniques. While there are features which are consistent between the 3 techniques, such as the evidence of the equinoctial asymmetry, there are also significant differences between the techniques both in terms of trends and absolute values. It is clear from this and previous studies that the high-latitude representation of the thermospheric neutral winds from the empirical Horizontal Wind Model (HWM), though improved from earlier versions, lacks accuracy in many conditions. The relative merits of each technique are discussed and while none of the techniques provides the perfect data set to address model performance at high-latitude, one or more needs to be included in future HWM reformulations. Key words. Meteorology and atmospheric dynamics (thermospheric dynamics), Ionosphere (ionosphere-atmosphere interactions, auroral ionosphere)

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