scholarly journals Migrating tide climatologies measured by a high-latitude array of SuperDARN HF-radars

2020 ◽  
Author(s):  
Willem E. van Caspel ◽  
Patrick J. Espy ◽  
Robert E. Hibbins ◽  
John P. McCormack
Keyword(s):  
High Latitude ◽  
Lower Thermosphere ◽  
Late Summer ◽  
Meridional Wind ◽  
Semidiurnal Tide ◽  
Planetary Scale ◽  
Global Environmental ◽  
Wind Measurements ◽  
Year 2000 ◽  
Polarization Phase

Abstract. This study uses hourly meteor wind measurements from a longitudinal array of 10 high-latitude SuperDARN HF-radars to isolate the migrating diurnal, semidiurnal and terdiurnal tidal modes at Mesosphere-Lower-Thermosphere (MLT) heights. The planetary-scale array of radars covers 180 degrees of longitude, with eight out of 10 radars being in near-continuous operation since the year 2000. Time series spanning 16 years of tidal amplitudes and phases in both zonal and meridional wind are presented, along with their respective annual climatologies. The method to isolate the migrating tidal modes from SuperDARN meteor winds is validated using two years of winds from NAVGEM-HA (Navy Global Environmental Model – High Altitude). The validation steps demonstrate that, given the geographical spread of the radar stations, the derived tidal modes are most closely representative of the migrating tides at 60° N. Some of the main characteristics of the observed migrating tides are that the semidiurnal tide shows sharp phase jumps around the equinoxes and peak amplitudes during late summer, and that the terdiurnal tide shows a pronounced secondary amplitude peak around DOY 260. In addition, the diurnal tide is found to show a bi-modal circular polarization phase relation between summer and winter.

scholarly journals Migrating tide climatologies measured by a high-latitude array of SuperDARN HF radars

2020 ◽  
Vol 38 (6) ◽  
pp. 1257-1265
Author(s):  
Willem E. van Caspel ◽  
Patrick J. Espy ◽  
Robert E. Hibbins ◽  
John P. McCormack
Keyword(s):  
High Latitude ◽  
Lower Thermosphere ◽  
Meridional Wind ◽  
Planetary Scale ◽  
Wind Measurements ◽  
Early Fall ◽  
Analysis System ◽  
Year 2000 ◽  
Polarization Phase ◽  
Meteorological Analysis

Abstract. This study uses hourly meteor wind measurements from a longitudinal array of 10 high-latitude SuperDARN high-frequency (HF) radars to isolate the migrating diurnal, semidiurnal, and terdiurnal tides at mesosphere–lower-thermosphere (MLT) altitudes. The planetary-scale array of radars covers 180∘ of longitude, with 8 out of 10 radars being in near-continuous operation since the year 2000. Time series spanning 16 years of tidal amplitudes and phases in both zonal and meridional wind are presented, along with their respective annual climatologies. The method to isolate the migrating tides from SuperDARN meteor winds is validated using 2 years of winds from a high-altitude meteorological analysis system. The validation steps demonstrate that, given the geographical spread of the radar stations, the derived tidal modes are most closely representative of the migrating tides at 60∘ N. Some of the main characteristics of the observed migrating tides are that the semidiurnal tide shows sharp phase jumps around the equinoxes and peak amplitudes during early fall and that the terdiurnal tide shows a pronounced secondary amplitude peak around day of year (DOY) 265. In addition, the diurnal tide is found to show a bi-modal circular polarization phase relation between summer and winter.

Observations of migrating tides in the mid-latitude MLT using an array of SuperDARN HF-radars

2020 ◽  
Author(s):  
Willem E. van Caspel ◽  
Patrick J. Espy ◽  
Robert E. Hibbins ◽  
John P. McCormack
Keyword(s):  
Lower Thermosphere ◽  
Atmospheric Tides ◽  
Horizontal Wind ◽  
Meteor Radar ◽  
Planetary Scale ◽  
Global Environmental ◽  
Synoptic Wind ◽  
Single Station ◽  
Wind Measurements ◽  
Wave Surfaces

<p>Solar thermal (migrating) atmospheric tides play an important role in shaping the day-to-day and seasonal variability of the Mesosphere-Lower-Thermosphere (MLT) region. Due the planetary scale of the migrating tides, observations have, however, remained sparse. This study uses meteor-echo wind measurements from a longitudinal array of SuperDARN HF-radars to isolate the amplitude and phase of the migrating diurnal, semidiurnal, and terdiurnal tide. The array of SuperDARN radars, covering nearly 180 degrees longitude at 60±5 degrees North, provide hourly horizontal wind measurements at approximately 95km altitude. The migrating components of the tides are isolated by fitting wave surfaces in space and time. The results are compared with global synoptic wind analyses from the high-altitude version of the Navy Global Environmental Model (NAVGEM-HA) to validate the method. The tides are also compared against those measured at a single station by the Trondheim (66N, 10E) meteor radar. We will present the method, a comparison between (migrating) tidal components in SuperDARN, NAVGEM-HA and the Trondheim meteor radar between 2014 and 2015, and migrating tide climatologies based on 21 years of SuperDARN data.</p>

scholarly journals A comparison of 11-year mesospheric and lower thermospheric winds determined by meteor and MF radar at 69 ° N

2017 ◽  
Vol 35 (4) ◽  
pp. 893-906 ◽  
Author(s):  
Sven Wilhelm ◽  
Gunter Stober ◽  
Jorge L. Chau
Keyword(s):  
Lower Thermosphere ◽  
Meridional Wind ◽  
Correction Factors ◽  
Data Set ◽  
Wind Measurements ◽  
Mesosphere And Lower Thermosphere ◽  
Thermospheric Winds ◽  
Good Agreement ◽  
Mlt Region ◽  
Mf Radar

Abstract. The Andenes Meteor Radar (MR) and the Saura Medium Frequency (MF) Radar are located in northern Norway (69° N, 16° E) and operate continuously to provide wind measurements of the mesosphere and lower thermosphere (MLT) region. We compare the two systems to find potential biases between the radars and combine the data from both systems to enhance altitudinal coverage between 60 and 110 km. The systems have altitudinal overlap between 78 and 100 km at which we compare winds and tides on the basis of hourly winds with 2 km altitude bins. Our results indicate reasonable agreement for the zonal and meridional wind components between 78 and 92 km. An exception to this is the altitude range below 84 km during the summer, at which the correlation decreases. We also compare semidiurnal and diurnal tides according to their amplitudes and phases with good agreement below 90 km for the diurnal and below 96 km for the semidiurnal tides. Based on these findings we have taken the MR data as a reference. By comparing the MF and MR winds within the overlapping region, we have empirically estimated correction factors to be applied to the MF winds. Existing gaps in that data set will be filled with weighted MF data. This weighting is done due to underestimated wind values of the MF compared to the MR, and the resulting correction factors fit to a polynomial function of second degree within the overlapping area. We are therefore able to construct a consistent and homogenous wind from approximately 60 to 110 km.

Influence of geomagnetic disturbances on midlatitude mesosphere/lower thermosphere mean winds and tides 

2021 ◽  
Author(s):  
Christoph Jacobi ◽  
Friederike Lilienthal ◽  
Dmitry Korotyshkin ◽  
Evgeny Merzlyakov ◽  
Gunter Stober
Keyword(s):  
Lower Thermosphere ◽  
Meridional Wind ◽  
Vertical Profiles ◽  
Semidiurnal Tide ◽  
Geomagnetic Disturbances ◽  
Noticeable Effect ◽  
Zonal Winds ◽  
The Mean ◽  
Mesosphere And Lower Thermosphere ◽  
Midlatitude Mesosphere

<p>Observations of upper mesosphere/lower thermosphere (MLT) wind have been performed at Collm (51°N, 13°E) and Kazan (56°N, 49°E), using two SKiYMET all-sky meteor radars with similar configuration. Daily vertical profiles of mean winds and tidal amplitudes have been constructed from hourly horizontal winds. We analyze the response of mean winds and tidal amplitudes to geomagnetic disturbances. To this end we compare winds and amplitudes for very quiet (Ap ≤ 5) and unsettled/disturbed (Ap ≥ 20) geomagnetic conditions. Zonal winds in both the mesosphere and lower thermosphere are weaker during disturbed conditions for both summer and winter. The summer equatorward meridional wind jet is weaker for disturbed geomagnetic conditions. Tendencies over Collm and Kazan for geomagnetic effects on mean winds qualitatively agree during most of the year. For the diurnal tide, amplitudes in summer are smaller in the mesosphere but greater in the lower thermosphere, but no clear tendency is seen for winter. Semidiurnal tidal amplitudes increase during geomagnetic active days in summer and winter. Terdiurnal amplitudes are slightly reduced in the mesosphere during disturbed days, but no clear effect is visible for the lower thermosphere. Overall, while there is a noticeable effect of geomagnetic variability on the mean wind, the effect on tidal amplitudes, except for the semidiurnal tide, is relatively small and partly different over Collm and Kazan.</p>

scholarly journals On the longitudinal structure of the transient day-to-day variation of the semidiurnal tide in the mid-latitude lower thermosphere − I. Winter season

2001 ◽  
Vol 19 (5) ◽  
pp. 545-562 ◽  
Author(s):  
E. G. Merzlyakov ◽  
Yu. I. Portnyagin ◽  
C. Jacobi ◽  
N. J. Mitchell ◽  
H. G. Muller ◽  
...  
Keyword(s):  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Winter Season ◽  
Semidiurnal Tide ◽  
Longitudinal Structure ◽  
Transient Behaviour ◽  
Meteorology And Atmospheric Dynamics ◽  
S Transform ◽  
Wind Measurements ◽  
Waves And Tides

Abstract. The longitudinal structure of the day-to-day variations of semidiurnal tide amplitudes is analysed based on coordinated mesosphere/lower thermosphere wind measurements at several stations during three winter campaigns. Possible excitation sources of these variations are discussed. Special attention is given to a nonlinear interaction between the semidiurnal tide and the day-to-day mean wind variations. Data processing includes the S-transform analysis which takes into account transient behaviour of secondary waves. It is shown that strong tidal modulations appear during a stratospheric warming and may be caused by aperiodic mean wind variations during this event.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides)

scholarly journals Influence of geomagnetic disturbances on mean winds and tides in the mesosphere/lower thermosphere at midlatitudes

2021 ◽  
Vol 19 ◽  
pp. 185-193
Author(s):  
Christoph Jacobi ◽  
Friederike Lilienthal ◽  
Dmitry Korotyshkin ◽  
Evgeny Merzlyakov ◽  
Gunter Stober
Keyword(s):  
Lower Thermosphere ◽  
Meridional Wind ◽  
Vertical Profiles ◽  
Semidiurnal Tide ◽  
Geomagnetic Disturbances ◽  
Noticeable Effect ◽  
Clear Tendency ◽  
Zonal Winds ◽  
The Mean ◽  
Mesosphere And Lower Thermosphere

Abstract. Observations of upper mesosphere/lower thermosphere (MLT) wind have been performed at Collm (51.3∘ N, 13.0∘ E) and Kazan (56∘ N, 49∘ E), using two SKiYMET all-sky meteor radars with similar configuration. Daily vertical profiles of mean winds and tidal amplitudes have been constructed from hourly horizontal winds. We analyse the response of mean winds and tidal amplitudes to geomagnetic disturbances. To this end, we compare winds and amplitudes for very quiet (Ap ≤ 5) and unsettled/disturbed (Ap ≥ 20) geomagnetic conditions. Zonal winds in both the mesosphere and lower thermosphere are weaker during disturbed conditions for both summer and winter. The summer equatorward meridional wind jet is weaker for disturbed geomagnetic conditions. Tendencies for geomagnetic effects on mean winds over Collm and Kazan qualitatively agree during most of the year. For the diurnal tide, amplitudes in summer are smaller in the mesosphere and greater in the lower thermosphere, but no clear tendency is seen for winter. Semidiurnal tidal amplitudes increase during geomagnetic active days in summer and winter. Terdiurnal amplitudes are slightly reduced in the mesosphere during disturbed days, but no clear effect is visible for the lower thermosphere. Overall, while there is a noticeable effect of geomagnetic variability on the mean wind, the effect on tidal amplitudes, except for the semidiurnal tide, is relatively small and partly different over Collm and Kazan.

scholarly journals The summertime 12-h wind oscillation with zonal wavenumber <i>s</i> = 1 in the lower thermosphere over the South Pole

1998 ◽  
Vol 16 (7) ◽  
pp. 828-837 ◽  
Author(s):  
Y. I. Portnyagin ◽  
J. M. Forbes ◽  
N. A. Makarov ◽  
E. G. Merzlyakov ◽  
S. Palo
Keyword(s):  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Thermal Excitation ◽  
South Pole ◽  
Planetary Scale ◽  
Zonal Wavenumber ◽  
Wind Measurements ◽  
Waves And Tides ◽  
Thermospheric Dynamics

Abstract. Meteor radar measurements of winds near 95 km in four azimuth directions from the geographic South Pole are analyzed to reveal characteristics of the 12-h oscillation with zonal wavenumber one (s=1). The wind measurements are confined to the periods from 19 January 1995 through 26 January 1996 and from 21 November 1996 through 27 January 1997. The 12-h s=1 oscillation is found to be a predominantly summertime phenomenon, and is replaced in winter by a spectrum of oscillations with periods between 6 and 11.5 h. Both summers are characterized by minimum amplitudes (5–10 ms–1) during early January and maxima (15–20 ms–1) in November and late January. For 10-day means of the 12-h oscillation, smooth evolutions of phase of order 4–6 h occur during the course of the summer. In addition, there is considerable day-to-day variability (±5–10 ms–1 in amplitude) with distinct periods (i.e., ~5 days and ~8 days) which suggests modulation by planetary-scale disturbances. A comparison of climatological data from Scott Base, Molodezhnaya, and Mawson stations suggests that the 12-h oscillation near 78°S is s=1, but that at 68°S there is probably a mixture between s=1 and other zonal wavenumber oscillations (most probably s=2). The mechanism responsible for the existence of the 12-h s=1 oscillation has not yet been identified. Possible origins discussed herein include in situ excitation, nonlinear interaction between the migrating semidiurnal tide and a stationary s=1 feature, and thermal excitation in the troposphere.Key words. Meteorology and atmospheric dynamics · Middle atmosphere dynamics · Thermospheric dynamics · Waves and tides

scholarly journals Seasonal and Local Solar Time Variation of the Meridional Wind at 95 km from Observations of the 11.072-GHz Ozone Line and the 557.7-nm Oxygen Line

2016 ◽  
Vol 33 (7) ◽  
pp. 1355-1361 ◽  
Author(s):  
Alan E. E. Rogers ◽  
Philip J. Erickson ◽  
Larisa P. Goncharenko ◽  
Omar B. Alam ◽  
John Noto ◽  
...  
Keyword(s):  
New York ◽  
Wind Velocity ◽  
Low Cost ◽  
Lower Thermosphere ◽  
Meridional Wind ◽  
Gradual Transition ◽  
Local Solar Time ◽  
Satellite Television ◽  
Solar Time ◽  
Wind Measurements

AbstractGround-based spectrometers have been deployed to measure the concentration, velocity, and temperature of ozone in the mesosphere and lower thermosphere (MLT), using low-cost satellite television electronics to observe the 11.072-GHz line of ozone. The ozone line was observed at an altitude near 95 km at 38°N, 71°W using three spectrometers located at the Massachusetts Institute of Technology’s Haystack Observatory (Westford, Massachusetts), Chelmsford High School (Chelmsford, Massachusetts), and Union College (Schenectady, New York), each pointed south at 8° elevation. Observations from 2009 through 2014 were used to derive the nightly averaged seasonal variation of the 95-km altitude meridional wind velocity, as well as the seasonally averaged variation of the meridional wind with local solar time. The results indicate a seasonal trend in which the winds at 95 km are directed southward at about 10 m s−1 in the summer of the Northern Hemisphere and northward at about 10 m s−1 in the winter. Nighttime data from −5 to +5 local solar time show a gradual transition of the meridional wind velocity from about −20 to 20 m s−1. These variations correlate well with nighttime wind measurements using 557.7-nm optical airglow observations from the Millstone Hill high-resolution Fábry–Perot interferometer (FPI) in Westford.

scholarly journals Planetary wave seasonality from meteor wind measurements at 7.4° S and 22.7° S

2014 ◽  
Vol 32 (5) ◽  
pp. 519-531 ◽  
Author(s):  
L. R. Araújo ◽  
L. M. Lima ◽  
P. P. Batista ◽  
B. R. Clemesha ◽  
H. Takahashi
Keyword(s):  
Seasonal Cycle ◽  
Lower Thermosphere ◽  
Austral Summer ◽  
Observation Data ◽  
Austral Spring ◽  
Quasi Biennial Oscillation ◽  
Planetary Scale ◽  
Annual Behavior ◽  
Wind Measurements

Abstract. In this study we have used wind observation data from the mesosphere and lower thermosphere (MLT) region, obtained from meteor radar measurements in São João do Cariri (7.4° S, 36.5° W) from July 2004 to December 2008 and in Cachoeira Paulista (22.7° S, 45.0° W) from January 2002 to July 2006 and from September 2007 to November 2008. From the spectral analysis it was possible to identify the presence of planetary-scale oscillations in the hourly winds for the two latitudes and to study their transient character, which allowed elaboration of a climatology of planetary oscillation signatures. Planetary waves with periods near 2-days, 6–7 days, and 16 days were focussed on in this study. The quasi-2-day waves in the meteoric winds showed a seasonal cycle, with intense amplitudes occurring after the austral summer solstice and extending until the end of the season. The vertical wavelengths of the 2-day wave over Cachoeira Paulista were larger than those at São João do Cariri. A possible modulation of the quasi-2-day wave amplitudes by the quasi-biennial oscillation (QBO) has been observed only at São João do Cariri. The 6–7 day oscillations presented more intense amplitudes during August–November but were present with lower amplitudes during March–April at both sites. The 6–7 day vertical wavelengths over São João do Cariri were larger than at Cachoeira Paulista. The 6–7 day amplitudes exhibited intra-seasonal and annual behavior, however, there was no clear evidence of QBO modulation. The 16-day oscillations showed a seasonal cycle at São João do Cariri, with amplifications from austral spring to mid-summer and weaker amplitudes from autumn until early winter, however, there was no clear seasonality over Cachoeira Paulista. The 16-day vertical wavelengths have assumed values of λz ~ 45–85 km over both sites. 16-day wave amplitudes at the two sites showed different long-term behaviors.

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