scholarly journals Characteristics of Stratospheric Winds over Jiuquan (41.1°N, 100.2°E) Using Rocketsonde Data in 1967–2004

2017 ◽  
Vol 34 (3) ◽  
pp. 657-667 ◽  
Author(s):  
Z. Sheng ◽  
J. W. Li ◽  
Y. Jiang ◽  
S. D. Zhou ◽  
W. L. Shi
Keyword(s):  
Zonal Wind ◽  
Middle Atmosphere ◽  
Correlation Coefficients ◽  
Meridional Wind ◽  
Horizontal Wind ◽  
Cycle Period ◽  
Observation Data ◽  
Wind Fields ◽  
Zonal Winds ◽  
Model Research

AbstractStratospheric winds play a significant role in middle atmosphere dynamics, model research, and carrier rocket experiments. For the first time, 65 sets of rocket sounding experiments conducted at Jiuquan (41.1°N, 100.2°E), China, from 1967 to 2004 are presented to study horizontal wind fields in the stratosphere. At a fixed height, wind speed obeys the lognormal distribution. Seasonal mean winds are westerly in winter and easterly in summer. In spring and autumn, zonal wind directions change from the upper to the lower stratosphere. The monthly zonal mean winds have an annual cycle period with large amplitudes at high altitudes. The correlation coefficients for zonal winds between observations and the Horizontal Wind Model (HWM) with all datasets are 0.7. The MERRA reanalysis is in good agreement with rocketsonde data according to the zonal winds comparison with a coefficient of 0.98. The sudden stratospheric warming is an important contribution to biases in the HWM, because it changes the zonal wind direction in the midlatitudes. Both the model and the reanalysis show dramatic meridional wind differences with the observation data.

scholarly journals FPI observations of nighttime mesospheric and thermospheric winds in China and their comparisons with HWM07

2013 ◽  
Vol 31 (8) ◽  
pp. 1365-1378 ◽  
Author(s):  
W. Yuan ◽  
X. Liu ◽  
J. Xu ◽  
Q. Zhou ◽  
G. Jiang ◽  
...  
Keyword(s):  
Zonal Wind ◽  
Annual Variation ◽  
Middle Atmosphere ◽  
Geomagnetic Latitude ◽  
Meridional Wind ◽  
Central China ◽  
Horizontal Wind ◽  
Zonal Winds ◽  
Meridional Winds ◽  
First Time

Abstract. We analyzed the nighttime horizontal neutral winds in the middle atmosphere (~ 87 and ~ 98 km) and thermosphere (~ 250 km) derived from a Fabry–Perot interferometer (FPI), which was installed at Xinglong station (40.2° N, 117.4° E) in central China. The wind data covered the period from April 2010 to July 2012. We studied the annual, semiannual and terannual variations of the midnight winds at ~ 87 km, ~ 98 km and ~ 250 km for the first time and compared them with Horizontal Wind Model 2007 (HWM07). Our results show the following: (1) at ~ 87 km, both the observed and model zonal winds have similar phases in the annual and semiannual variations. However, the HWM07 amplitudes are much larger. (2) At ~ 98 km, the model shows strong eastward wind in the summer solstice, resulting in a large annual variation, while the observed strongest component is semiannual. The observation and model midnight meridional winds agree well. Both are equatorward throughout the year and have small amplitudes in the annual and semiannual variations. (3) There are large discrepancies between the observed and HWM07 winds at ~ 250 km. This discrepancy is largely due to the strong semiannual zonal wind in the model and the phase difference in the annual variation of the meridional wind. The FPI annual variation coincides with the results from Arecibo, which has similar geomagnetic latitude as Xinglong station. In General, the consistency of FPI winds with model winds is better at ~ 87 and ~ 98 km than that at ~ 250 km. We also studied the seasonally and monthly averaged nighttime winds. The most salient features include the following: (1) the seasonally averaged zonal winds at ~ 87 and ~ 98 km typically have small variations throughout the night. (2) The model zonal and meridional nighttime wind variations are typically much larger than those of observations at ~ 87 km and ~ 98 km. (3) At ~ 250 km, model zonal wind compares well with the observation in the winter. For spring and autumn, the model wind is more eastward before ~ 03:00 LT but more westward after. The observed nighttime zonal and meridional winds on average are close to zero in the summer and autumn, which indicates a lack of strong stable tides. The consistency of FPI zonal wind with model wind at ~ 250 km is better than the meridional wind.

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 A Wind Study of Venus’s Cloud Top: New Doppler Velocimetry Observations

Atmosphere ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 2
Author(s):  
Ruben Gonçalves ◽  
Pedro Machado ◽  
Thomas Widemann ◽  
Francisco Brasil ◽  
José Ribeiro
Keyword(s):  
Spatial Variability ◽  
Local Time ◽  
Zonal Wind ◽  
Meridional Wind ◽  
Space Mission ◽  
Horizontal Wind ◽  
Doppler Velocimetry ◽  
Middle Latitudes ◽  
Wind Velocities ◽  
Wind Stability

At Venus’s cloud top, the circulation is dominated by the superroration, where zonal wind speed peaks at ∼100 ms−1, in the low-to-middle latitudes. The constraining of zonal and meridional circulations is essential to understanding the mechanisms driving the superrotation of Venus’s atmosphere, which are still poorly understood. We present new Doppler velocimetry measurements of horizontal wind velocities at Venus’s cloud top, around 70 km altitude. These results were based on March 2015 observations at the Canada–France–Hawaii Telescope (CFHT, Mauna Kea, Hawaii), using ESPaDOnS. The Doppler velocimetry method used has already successfully provided zonal and meridional results in previous works led by P. Machado and R. Gonçalves, proving to be a good reference ground-based technique in the study of the dynamics of Venus’s atmosphere. These observations were carried out between 27 and 29 March 2015, using the Echelle SpectroPolarimetric Device for the Observation of Stars (ESPaDOnS) which provides simultaneous visible-near IR spectra from 370 to 1050 nm, with a spectral resolution of 81000 allowing wind field characterization in the scattered Franuhofer solar lines by Venus’s cloud top on the dayside. The zonal velocities are consistent with previous results while also showing evidence of spatial variability, along planetocentric latitude and longitude (local-time). The meridional wind circulation presents a notably constant latitudinal structure with null velocities at lower latitudes, below 10∘ N–S, and peak velocities of ∼30 ms−1, centered around 35∘ N–S. The uncertainty of the meridional wind results from ground observations is of the same order as the uncertainty of meridional wind retrieved by space-based observations using cloud-tracking, as also shown by previous work led by R. Gonçalves and published in 2020. These March 2015 measurements present a unique and valuable contribution to the study of horizontal wind at the cloud top, from a period when Doppler velocimetry was the only available method to do so, since no space mission was orbiting Venus between Venus Express ending in January 2015 and Akatsuki’s orbit insertion in December 2015. These results from new observations provide (1) constraints on zonal wind temporal and spatial variability (latitude and local time), (2) constraints on the meridional wind latitudinal profile, (3) additional evidence of zonal and meridional wind stability for the period between 2011 and 2015 (along previous Doppler results) (4) further evidence of the consistency and robustness of our Doppler velocimetry method.

scholarly journals Meteor radar observations of atmospheric waves in the equatorial mesosphere/lower thermosphere over Ascension Island

2004 ◽  
Vol 22 (2) ◽  
pp. 387-404 ◽  
Author(s):  
D. Pancheva ◽  
N. J. Mitchell ◽  
P. T. Younger
Keyword(s):  
Zonal Wind ◽  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Meridional Wind ◽  
Kelvin Wave ◽  
Vertical Wavelength ◽  
Period Range ◽  
Meridional Component ◽  
Ascension Island ◽  
Waves And Tides

Abstract. Some preliminary results about the planetary wave characteristics observed during the first seven months (October 2001-April 2002) of observations over Ascension Island (7.9°S, 14.4°W) are reported in this study. The zonal wind is dominated by the 3–7-day waves, while the meridional component – by the quasi-2-day wave. Two wave events in the zonal wind are studied in detail: a 3–4-day wave observed in the end of October/November and the 3–6-day wave in January/February. The moderate 3- and 3.2-day waves are interpreted as an ultra-fast Kelvin wave, while for the strong 4-day wave we are not able to make a firm decision. The 6-day wave is interpreted as a Doppler-shifted 5-day normal mode, due to its very large vertical wavelength (79km). The quasi-2-day wave seems to be present almost continuously in the meridional wind, but the strongest bursts are observed mainly in December and January. The observed period range is large, from 34 to 68h, with some clustering around 43–44 and 50h. The estimated vertical wavelengths indicate shorter lengths during the equinoxes, in the range of 25-30km, and longer ones, ∼40–50km, in January/February, when the 48-h wave is strongest. Key words. Meteorology and atmospheric dynamics middle atmosphere dynamics, waves and tides)

scholarly journals The Effects of Background Zonal and Meridional Winds on ENSO in a Coupled GCM

2020 ◽  
Vol 33 (6) ◽  
pp. 2075-2091 ◽  
Author(s):  
Bowen Zhao ◽  
Alexey Fedorov
Keyword(s):  
Zonal Wind ◽  
El Niño ◽  
Climate Model ◽  
El Nino ◽  
Meridional Wind ◽  
Wind Component ◽  
Coupled Models ◽  
Positive Feedbacks ◽  
Zonal Winds ◽  
Meridional Winds

AbstractChanges in background zonal wind in the tropical Pacific are often invoked to explain changes in ENSO properties. However, the sensitivity of ENSO to mean zonal winds has been thoroughly explored only in intermediate coupled models (following Zebiak and Cane), not in coupled GCMs. The role of mean meridional winds has received even less attention. Accordingly, the goal of this study is to examine systematically the effects of both zonal (equatorial) and meridional (cross-equatorial) background winds on ENSO using targeted experiments with a comprehensive climate model (CESM). Changes in the mean winds are generated by imposing heat flux forcing in two confined regions at a sufficient distance north and south of the equator. We find that the strengthening of either wind component reduces ENSO amplitude, especially eastern Pacific SST variability, and inhibits meridional swings of the intertropical convergence zone (ITCZ). The effect of zonal winds is generally stronger than that of meridional winds. A stability analysis reveals that the strengthening of zonal and meridional winds weakens the ENSO key positive feedbacks, specifically the zonal advection and thermocline feedbacks, which explains these changes. Zonal wind enhancement also intensifies mean upwelling and hence dynamical damping, leading to a further weakening of El Niño events. Ultimately, this study argues that the zonal and, to a lesser extent, meridional wind strengthening of the past decades may have contributed to the observed shift of El Niño characteristics after the year 2000.

Observed and simulated zonally asymmetric zonal wind patterns under NAO conditions

2021 ◽  
Author(s):  
Aslı İlhan ◽  
Deniz Demirhan ◽  
Yurdanur Ünal
Keyword(s):  
Zonal Wind ◽  
Impact Analysis ◽  
Middle Atmosphere ◽  
Incident Radiation ◽  
Extreme Weather Events ◽  
Winter Climate ◽  
Weather Patterns ◽  
Zonal Winds ◽  
Funding Program ◽  
Wind Patterns

<p>The North Atlantic Oscillation (NAO), coexistent meridional oscillation of subpolar Icelandic low and the subtropical Azores high dominates the Northern Hemispheric winter climate. Variability in the circulation of NAO may activate the extreme weather events, such as the enhanced zonal winds, in northeast America, Atlantic and Eurasia. On the other hand variability in the zonal wind patterns effects the position of the NAO events. It is more relevant to investigate the interaction between NAO and the weather patterns during the winter time since NAO is powerful during winter. Hence the wintertime weather systems are highly altered by such an impact. Analysis indicate that negative and positive phases of NAO mainly modulate the local cyclonic and anticyclonic wave characteristics and hence the zonally asymmetric circulation of the middle atmosphere. Zonal asymmetries in the weather patterns originate from ocean-continent temperature gradients and topographical contrasts after all solar incident radiation is almost uniform over the longitudes. Thus zonally asymmetric patterns for certain variables such as zonal winds show strong seasonal dependence and highly correlate with the climatological position of the NAO mainly in the winter hemisphere. In this study longitudinal differences in the zonal wind is analyzed in order to observe its strong influence on the evolution of NAO. Zonal asymmetries of zonal wind is examined by evaluating the deviation from zonal mean of the long term annual average of both winter and spring months from December to April. Zonal winds up to 100km for winter and spring is examined between 2006-2100 using CMIP5 MPI-ESM-MR RCP4.5 scenario for the extratropical and the polar latitudes. Additionally ERA5 reanalysis data is used to identify the ability of CMIP5 Reference Period (RP) data to capture the observed patterns for the years from 1979 to 2005.</p><p>Acknowledgements: This study is supported by TUBİTAK (The Scientific and Technology Research Council of Turkey), The Scientific and Technological Research Projects Funding Program, 1001. The projects number is 117Y327.</p>

scholarly journals Middle-atmospheric zonal and meridional wind profiles from polar, tropical and mid latitudes with the ground-based microwave Doppler wind radiometer WIRA

2014 ◽  
Vol 7 (7) ◽  
pp. 7717-7752
Author(s):  
R. Rüfenacht ◽  
A. Murk ◽  
N. Kämpfer ◽  
P. Eriksson ◽  
S. A. Buehler
Keyword(s):  
Zonal Wind ◽  
Signal To Noise Ratio ◽  
Optimal Estimation ◽  
Meridional Wind ◽  
Horizontal Wind ◽  
Data Series ◽  
Model Data ◽  
Set Up ◽  
Wind Profiles ◽  
Ecmwf Model

Abstract. WIRA is a ground-based microwave Doppler spectro radiometer specifically designed for the measurement of profiles of horizontal wind in the upper stratosphere and lower mesosphere region where no other continuously running measurement technique exists. A proof of principle has been delivered in a previous publication. Since a technical upgrade which improved the signal to noise ratio by a factor of 2.4 the full horizontal wind field comprising zonal and meridional wind profiles is continuously measured. A completely new retrieval based on optimal estimation has been set up. Its characteristics are detailed in the present paper. Since the start of the routine operation of the first prototype in September 2010, WIRA has been measuring at four different locations at polar, mid and tropical latitudes for time periods between 5.5 and 11 months. A comparison between the data series from WIRA and ECMWF model data revealed agreement within 10% in the stratospheric zonal wind. The meridional wind profiles agree within their error bars over the entire sensitive altitude range of WIRA. However, significant differences in the mesospheric zonal wind speed of up to 40% have been found.

scholarly journals Assessment of the ERA-Interim Winds Using High-Altitude Stratospheric Balloons

2017 ◽  
Vol 74 (6) ◽  
pp. 2065-2080 ◽  
Author(s):  
Fabrice Duruisseau ◽  
Nathalie Huret ◽  
Alice Andral ◽  
Claude Camy-Peyret
Keyword(s):  
Wind Speed ◽  
High Altitude ◽  
Middle Atmosphere ◽  
Meridional Wind ◽  
Horizontal Wind ◽  
Quasi Biennial Oscillation ◽  
Wind Variability ◽  
Wind Measurements ◽  
Biennial Oscillation ◽  
Balloon Measurements

Abstract This study focuses on the ability of ERA-Interim to represent wind variability in the middle atmosphere. The originality of the proposed approach is that wind measurements are deduced from the trajectories of zero-pressure balloons that can reach high-stratospheric altitudes. These balloons are mainly used to carry large scientific payloads. The trajectories of balloons launched above Esrange, Sweden, and Teresina, Brazil, from 2000 to 2011 were used to deduce zonal and meridional wind components (by considering the balloon as a perfect tracer at high altitude). Collected data cover several dynamical conditions associated with the winter and summer polar seasons and west and east phases of the quasi-biennial oscillation at the equator. Systematic comparisons between measurements and ERA-Interim data were performed for the two horizontal wind components, as well as wind speed and wind direction in the [100, 2]-hPa pressure range to deduce biases between the model and balloon measurements as a function of altitude. Results show that whatever the location and the geophysical conditions considered, biases between ERA-Interim and balloon wind measurements increase as a function of altitude. The standard deviation of the model–observation wind differences can attain more than 5 m s−1 at high altitude (pressure P < 20 hPa). A systematic ERA-Interim underestimation of the wind speed is observed and large biases are highlighted, especially for equatorial flights.

scholarly journals The Semiannual Oscillation of the Tropical Zonal Wind in the Middle Atmosphere Derived from Satellite Geopotential Height Retrievals

2017 ◽  
Vol 74 (8) ◽  
pp. 2413-2425 ◽  
Author(s):  
Anne K. Smith ◽  
Rolando R. Garcia ◽  
Andrew C. Moss ◽  
Nicholas J. Mitchell
Keyword(s):  
Zonal Wind ◽  
Geopotential Height ◽  
Middle Atmosphere ◽  
Dominant Mode ◽  
Quasi Biennial Oscillation ◽  
Zonal Winds ◽  
Broadband Emission ◽  
The Tropics ◽  
Biennial Oscillation ◽  
Semiannual Oscillation

Abstract The dominant mode of seasonal variability in the global tropical upper-stratosphere and mesosphere zonal wind is the semiannual oscillation (SAO). However, it is notoriously difficult to measure winds at these heights from satellite or ground-based remote sensing. Here, the balance wind relationship is used to derive monthly and zonally averaged zonal winds in the tropics from satellite retrievals of geopotential height. Data from the Aura Microwave Limb Sounder (MLS) cover about 12.5 yr, and those from the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) Sounding of the Atmosphere Using Broadband Emission Radiometry (SABER) cover almost 15 yr. The derived winds agree with direct wind observations below 10 hPa and above 80 km; there are no direct wind observations for validation in the intervening layers of the middle atmosphere. The derived winds show the following prominent peaks associated with the SAO: easterly maxima near the solstices at 1.0 hPa, westerly maxima near the equinoxes at 0.1 hPa, and easterly maxima near the equinoxes at 0.01 hPa. The magnitudes of these three wind maxima are stronger during the first cycle (January at 1.0 hPa and March at 0.1 and 0.01 hPa). The month and pressure level of the wind maxima shift depending on the phase of the quasi-biennial oscillation (QBO) at 10 hPa. During easterly QBO, the westerly maxima are shifted upward, are about 10 m s−1 stronger, and occur approximately 1 month later than those during the westerly QBO phase.

scholarly journals Observation of horizontal winds in the middle-atmosphere between 30° S and 55° N during the northern winter 2009–2010

2013 ◽  
Vol 13 (12) ◽  
pp. 6049-6064 ◽  
Author(s):  
P. Baron ◽  
D. P. Murtagh ◽  
J. Urban ◽  
H. Sagawa ◽  
S. Ochiai ◽  
...  
Keyword(s):  
Middle Atmosphere ◽  
Flow Direction ◽  
Space Station ◽  
Meridional Wind ◽  
Mean Difference ◽  
Quality Data ◽  
Absolute Value ◽  
Zonal Winds ◽  
The Mean ◽  
The Tropics

Abstract. Although the links between stratospheric dynamics, climate and weather have been demonstrated, direct observations of stratospheric winds are lacking, in particular at altitudes above 30 km. We report observations of winds between 8 and 0.01 hPa (~35–80 km) from October 2009 to April 2010 by the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on the International Space Station. The altitude range covers the region between 35–60 km where previous space-borne wind instruments show a lack of sensitivity. Both zonal and meridional wind components were obtained, though not simultaneously, in the latitude range from 30° S to 55° N and with a single profile precision of 7–9 m s–1 between 8 and 0.6 hPa and better than 20 m s–1 at altitudes above. The vertical resolution is 5–7 km except in the upper part of the retrieval range (10 km at 0.01 hPa). In the region between 1–0.05 hPa, an absolute value of the mean difference < 2 m s–1 is found between SMILES profiles retrieved from different spectroscopic lines and instrumental settings. Good agreement (absolute value of the mean difference of ~2 m s–1) is also found with the European Centre for Medium-Range Weather Forecasts (ECMWF) analysis in most of the stratosphere except for the zonal winds over the equator (difference > 5 m s−1). In the mesosphere, SMILES and ECMWF zonal winds exhibit large differences (> 20 m s–1), especially in the tropics. We illustrate our results by showing daily and monthly zonal wind variations, namely the semi-annual oscillation in the tropics and reversals of the flow direction between 50–55° N during sudden stratospheric warmings. The daily comparison with ECMWF winds reveals that in the beginning of February, a significantly stronger zonal westward flow is measured in the tropics at 2 hPa compared to the flow computed in the analysis (difference of ~20 m s–1). The results show that the comparison between SMILES and ECMWF winds is not only relevant for the quality assessment of the new SMILES winds, but it also provides insights on the quality of the ECMWF winds themselves. Although the instrument was not specifically designed for measuring winds, the results demonstrate that space-borne sub-mm wave radiometers have the potential to provide good quality data for improving the stratospheric winds in atmospheric models.

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