Interhemispheric Meridional Circulation During Sudden Stratospheric Warming

Laskar, F. I.; McCormack, J. P.; Chau, Jorge L.; Pallamraju, Duggirala; Hoffmann, Peter; Singh, Ravindra Pratap

doi:10.1029/2018ja026424

Cited by 34 publications

(45 citation statements)

References 51 publications

(102 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Above this level, NAVGEM-HA vertical resolution degrades significantly, as the vertical grid spacing increases from ∼ 3 km near 80 km altitude to more than 5 km near 100 km altitude. To date, NAVGEM-HA winds and tides up to 90 km altitude have been shown to be in good agreement with both ground-based MR observations, as reported in McCormack et al (2017), Eckermann et al (2018) and Laskar et al (2019), and with independent satellite-based wind observations, as reported in Dhadly et al (2018). The present study extends these initial validation studies to include, for the first time, validation with two independent ground-based data sets over a 12-month period.…”

Section: Navgem-ha Meteorological Analysessupporting

confidence: 78%

Comparative study between ground-based observations and NAVGEM-HA analysis data in the mesosphere and lower thermosphere region

et al. 2020

Self Cite

View full text Add to dashboard Cite

Abstract. Recent studies have shown that day-to-day variability of the migrating semidiurnal solar (SW2) tide within the mesosphere and lower thermosphere (MLT) is a key driver of anomalies in the thermosphere–ionosphere system. Here, we study the variability in both the amplitude and phase of SW2 using meteor radar wind and lidar temperature observations at altitudes of 75–110 km as well as wind and temperature output from the Navy Global Environmental Model – High Altitude (NAVGEM-HA), a high-altitude meteorological analysis system. Application of a new adaptive spectral filter technique to both local radar wind observations and global NAVGEM-HA analyses offers an important cross-validation of both data sets and makes it possible to distinguish between migrating and non-migrating tidal components, which is difficult using local measurements alone. Comparisons of NAVGEM-HA, meteor radar and lidar observations over a 12-month period show that the meteorological analyses consistently reproduce the seasonal as well as day-to-day variability in mean winds, mean temperatures and SW2 features from the ground-based observations. This study also examines in detail the day-to-day variability in SW2 during two sudden stratospheric warming, events that have been implicated in producing ionospheric anomalies. During this period, both meteor radar and NAVGEM-HA winds show a significant phase shift and amplitude modulation, but no signs of coupling to the lunar tide as previous studies have suggested. Overall, these findings demonstrate the benefit of combining global high-altitude meteorological analyses with ground-based observations of the MLT region to better understand the tidal variability in the atmosphere.

show abstract

Section: Navgem-ha Meteorological Analysessupporting

confidence: 78%

Comparative study between ground-based observations and NAVGEM-HA analysis data in the mesosphere and lower thermosphere region

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…For comparison with ground-based instruments, vertical profiles of NAVGEM-HA analyzed winds and temperatures are converted from the model vertical grid in geopotential altitude to a geometric altitude grid. To date, NAVGEM-HA winds and tides have been shown to be in good agreement with ground-based meteor radar observations (McCormack et al, 2017;Eckermann et al, 2018;Laskar et al, 2019;Stober et al, 2020) and with independent satellite-based wind observations as reported in Dhadly et al (2018). In the present study we employ NAVGEM-HA analyzed winds at 82.5 km altitude, staying below altitudes where effects of increased numerical diffusion imposed at the NAVGEM-HA upper boundary may impact the tides, to validate the method of extracting migrating tidal signatures from the SD meteor wind data.…”

Section: Navgem-hasupporting

confidence: 58%

“…NAVGEM-HA is a data assimilation and modeling system that extends from the surface to the lower thermosphere. In addition to standard operational meteorological observations in the troposphere and stratosphere, NAVGEM-HA assimilates satellite-based observations of temperature, ozone, and water vapor in the stratosphere, mesosphere, and lower thermosphere (McCormack et al, 2017). NAVGEM-HA output is on a 1 • latitude and longitude grid with a temporal frequency of 3 h, staying above the spatial and temporal Nyquist frequency of the tides studied in this work.…”

Section: Navgem-hamentioning

confidence: 99%

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

et al. 2020

Self Cite

View full text Add to dashboard Cite

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.

show abstract

“…In 200 both studies mentioned above, it was confirmed that large-scale wave disturbances are the main driving force of the RMC due to the transfer of energy and angular momentum in the middle atmosphere and the MLT region. Laskar et al (2019) showed a significant weakening (up to a reversal) of both the mean and residual meridional circulation at the MLT heights during SSW observed in winters 2009/10 and 2012/13, leading to significant temperature fluctuations in the stratosphere of both hemispheres, which correspond our results discussed above.…”

Section: Residual Circulation At the Different Sw Stagessupporting

confidence: 88%

Modelling the residual mean meridional circulation at different stages of stratospheric warming events

Koval¹,

Bakhareva²,

Didenko³

et al. 2020

Preprint

View full text Add to dashboard Cite

Abstract. Ensemble simulation of the general atmospheric circulation of the middle and upper atmosphere up to the lower thermosphere is performed using the 3-D nonlinear mechanistic numerical model MUAM. Residual mean meridional circulation (RMC) in terms of the Transformed Eulerian Mean is calculated for the boreal winter and changes in its vertical and meridional velocity components during different phases of simulated composite stratospheric warming (SW) events are studied. The simulation results show general decrease in RMC velocity components up to 30 % during and after SW in the mesosphere and lower thermosphere of the Northern Hemisphere. There are also increases in the downward and northward velocities at altitudes 50–70 km at the northern high latitudes. Associated changes in adiabatic heating/cooling rates can contribute to heating the stratosphere and cooling the mesosphere during the composite SW. The changes in the transport of conservative species (like ozone) during SWs are estimated. Weakening of ozone fluxes at the middle latitudes of the Northern Hemisphere may reach 30 % during SWs and 30–40 % after the events at the altitudes of stratospheric maximum of ozone concentration. Such statistically confident simulations of RMC reactions on SWs at altitudes up to the lower thermosphere are performed for the first time. The study of the residual meridional circulation is useful for effective analysis of wave impacts on the mean flow and for diagnostics of the transport of atmospheric gas species in the atmosphere.

show abstract

Interhemispheric Meridional Circulation During Sudden Stratospheric Warming

Cited by 34 publications

References 51 publications

Comparative study between ground-based observations and NAVGEM-HA analysis data in the mesosphere and lower thermosphere region

Comparative study between ground-based observations and NAVGEM-HA analysis data in the mesosphere and lower thermosphere region

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

Modelling the residual mean meridional circulation at different stages of stratospheric warming events

Contact Info

Product

Resources

About