The role of the QBO in the inter-hemispheric coupling of summer  mesospheric temperatures

Espy, P. J.; Fernandez, Susana; Forkman, Peter; Murtagh, Donal; Stegman, J.

doi:10.5194/acpd-10-23403-2010

Cited by 11 publications

(26 citation statements)

References 46 publications

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“…Earlier, She and Krueger [2004], using the same data set but with shorter time series have reported a solar response of the order of 2.9 ± 1.5 K/decade at the mesopause region. Espy et al [2011] have used a 10 year time series of July mesospheric temperatures derived from the hydroxyl (OH) nightglow. These measurements of Espy et al [2011] were made from Stockholm, Sweden (59.5°N, 18.2°E), during the summers of 1991 and 1993 and then continuously from 1993 through 1998.…”

Section: Solar Response In the Mesopause Regionmentioning

confidence: 99%

“… Espy et al [2011] have used a 10 year time series of July mesospheric temperatures derived from the hydroxyl (OH) nightglow. These measurements of Espy et al [2011] were made from Stockholm, Sweden (59.5°N, 18.2°E), during the summers of 1991 and 1993 and then continuously from 1993 through 1998. After 1998, the instrument was moved to Onsala, Sweden (57.4°N, 11.9°E), and data collection continued through 2000.…”

Section: Solar Response In the Mesopause Regionmentioning

confidence: 99%

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Long-term trends in the temperature of the mesosphere/lower thermosphere region: 2. Solar response

Beig

2011

J. Geophys. Res.

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Understanding trends in any atmospheric quantity typically requires the ability to distinguish between naturally occurring processes that result in trends, such as the 11 year solar cycle, and potential anthropogenic secular trends that occur simultaneously. After the review of mesospheric and lower thermospheric temperature response to solar activity by Beig et al. (2008), a few new results along with some modified results by revisiting the older data sets have been reported recently. Main improvement is due to the length of data series and amount of data which have been accounted in recent years. This article summarizes the progress made in the field of temperature variability due to changing solar activity as reported recently. Recent investigations revealed that the solar signal becomes stronger with increasing latitude in the mesosphere. Temperature response to solar activity at the lower part of mesopause region is around a few degrees per 100 solar flux units (sfu), which becomes stronger (4–5 K/100 sfu) in the upper part of this region in both hemispheres. The overall global picture indicates that the solar signal in the mesopause region temperature in the Northern Hemisphere is relatively stronger in recent time in a majority of locations compared to results reported in earlier reviews.

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Section: Solar Response In the Mesopause Regionmentioning

confidence: 99%

Section: Solar Response In the Mesopause Regionmentioning

confidence: 99%

Long-term trends in the temperature of the mesosphere/lower thermosphere region: 2. Solar response

Beig

2011

J. Geophys. Res.

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“…It is most probably generated by momentum deposition of gravity waves selectively filtered by the stratospheric winds [ Mayr et al , ; De Wit et al , ]. At high latitudes, a mesospheric QBO signal has been previously observed in planetary wave activity [ Espy et al , ; Hibbins et al , ], semidiurnal tides [ Jarvis , ; Hibbins et al , , ], diurnal tides [ Xu et al , ], temperatures [ Espy et al , ; Mayr et al , ], and winds [ Ford et al , ; Hibbins et al , ]. However, at midlatitudes, the mesospheric QBO signal is comparatively less understood.…”

Section: Introductionmentioning

confidence: 99%

HF radar observations of a quasi‐biennial oscillation in midlatitude mesospheric winds

et al. 2016

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The equatorial quasi‐biennial oscillation (QBO) is known to be an important source of interannual variability in the middle‐ and high‐latitude stratosphere. The influence of the QBO on the stratospheric polar vortex in particular has been extensively studied. However, the impact of the QBO on the winds of the midlatitude mesosphere is much less clear. We have applied 13 years (2002–2014) of data from the Saskatoon Super Dual Auroral Radar Network HF radar to show that there is a strong QBO signature in the midlatitude mesospheric zonal winds during the late winter months. We find that the Saskatoon mesospheric winds are related to the winds of the equatorial QBO at 50 hPa such that the westerly mesospheric winds strengthen when QBO is easterly, and vice versa. We also consider the situation in the late winter Saskatoon stratosphere using the European Centre for Medium‐Range Weather Forecasts ERA‐Interim reanalysis data set. We find that the Saskatoon stratospheric winds between 7 hPa and 70 hPa weaken when the equatorial QBO at 50 hPa is easterly, and vice versa. We speculate that gravity wave filtering from the QBO‐modulated stratospheric winds and subsequent opposite momentum deposition in the mesosphere plays a major role in the appearance of the QBO signature in the late winter Saskatoon mesospheric winds, thereby coupling the equatorial stratosphere and the midlatitude mesosphere.

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“…Vertical shears produced by the MQBO can affect the propagation of migrating solar tides by altering the width of the tropical waveguide through which tides propagate into the dynamo region (Garcia & Sassi, ; McLandress , ; Sassi et al, ). In the extratropics, the QBO is known to modulate the propagation of PWs into the winter stratosphere and mesosphere, producing a stronger or weaker winter polar vortex through the Holton‐Tan effect (Holton & Tan, ). This in turn influences GW fluxes into the winter MLT region (de Wit et al, ) as well as polar mesopause temperatures in the summer hemisphere through changes in the wave‐driven residual meridional circulation (Espy et al, ). The tropical MQBO may also modulate the amplitudes of migrating and non‐migrating tides in the extratopics through nonlinear wave‐wave interactions. This mechanism involves preferential ducting of quasi‐stationary PW 1 from the Southern Hemisphere to the Northern Hemisphere during the westward QBO phase.…”

Section: Interseasonal Variabilitymentioning

confidence: 99%

“…In the extratropics, the QBO is known to modulate the propagation of PWs into the winter stratosphere and mesosphere, producing a stronger or weaker winter polar vortex through the Holton‐Tan effect (Holton & Tan, ). This in turn influences GW fluxes into the winter MLT region (de Wit et al, ) as well as polar mesopause temperatures in the summer hemisphere through changes in the wave‐driven residual meridional circulation (Espy et al, ).…”

Section: Interseasonal Variabilitymentioning

confidence: 99%

Whole Atmosphere Coupling on Intraseasonal and Interseasonal Time Scales: A Potential Source of Increased Predictive Capability

2019

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Recent advances in developing accurate, physics‐based models of the coupled ionosphere‐thermosphere (CIT) system have now made these models an integral part of next‐generation space weather prediction capabilities. These advances have produced a better understanding of how the CIT is affected by variability in the neutral lower atmosphere. However, the impacts on the CIT of lower atmospheric variability over time scales with characteristic periods longer than ~10 days have received little attention, despite clear evidence of this variability in atmospheric circulation patterns throughout the stratosphere, mesosphere, and lower thermosphere. This review synthesizes the state of knowledge on long‐term variability (>10 days) originating in the lower atmosphere and its impacts on the CIT, highlighting the following critical points and challenges: (a) planetary wave oscillations are likely to couple the lower and upper atmospheres, especially those corresponding to normal modes of the atmosphere, but it remains unclear whether they impact the ionosphere directly via wind‐dynamo coupling, or indirectly via modulation of solar and lunar tides; (b) while fast moving planetary wave oscillations are ubiquitous in the CIT especially during solstices, there is only sporadic evidence that the slowest moving modes are also present in the upper atmosphere; (c) there is abundant evidence of long‐term variations of tidal amplitudes in the CIT, but how and why such variations occur still remain; (d) interseasonal variations associated with major tropospheric and stratospheric variability have been observed, but the physical pathways are still poorly understood.

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The role of the QBO in the inter-hemispheric coupling of summer mesospheric temperatures

Cited by 11 publications

References 46 publications

Long-term trends in the temperature of the mesosphere/lower thermosphere region: 2. Solar response

Long-term trends in the temperature of the mesosphere/lower thermosphere region: 2. Solar response

HF radar observations of a quasi‐biennial oscillation in midlatitude mesospheric winds

Whole Atmosphere Coupling on Intraseasonal and Interseasonal Time Scales: A Potential Source of Increased Predictive Capability

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