Neutral atmosphere temperature trends and variability at 90 km,  70 °N, 19 °E, 2003–2014

Holmen, S. E.; Hall, Chris M.; Tsutsumi, Masaki

doi:10.5194/acp-16-7853-2016

Cited by 21 publications

(20 citation statements)

References 59 publications

(95 reference statements)

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“…An extensive review byLaštovička (2017) of trends in MLT temperatures shows the results depend to some extent on whether pressure or geometric coordinates are used. In geometric coordinates, as used here, the trends near 90 km appear to be small, about ±0.5 K per decade Holmen et al (2016). analyzing temperatures using 90-km meteor observations made between2004 and 2015 at Tromsø, Norway (19E, 70N), found a significant trend of −11.6±4.1 K per decade in winter, but a negligible trend of −0.3 K±3.1 K per decade at the summer solstice.…”

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confidence: 77%

Trends and Variability in Vertical Winds in the Southern Hemisphere Summer Polar Mesosphere and Lower Thermosphere

et al. 2019

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Direct measurement of mean vertical velocities in the mesosphere‐lower thermosphere (60–110 km) is not possible due to their small values. Here we derive vertical velocities using the divergence of the mean meridional wind over the Antarctic summer pole using MF radar wind measurements made at Davis Station (69°S, 78°E) between 1994 and 2018. Estimates of vertical velocity are restricted to a 21‐day period centered just after solstice when the equatorward wind reaches its maximum value of about 15 m s−1 at heights near 90 km. The Medium Frequency (MF) radar winds are calibrated against colocated meteor wind radar observations. Neutral densities required for the vertical wind calculations are obtained from zonally averaged temperature measurements obtained by the MLS instrument aboard the AURA satellite. The estimated vertical velocities have peak values varying between 2 and 6 cm s−1 with significant interannual variability. While the peak values do not show significant long‐term change, there is a long‐term decrease in the mean height of maximum winds of about 0.6 km per decade that is statistically significant. The interannual variability is linked to the date of transition in the stratospheric zonal circulation from winter eastward to summer westward flow. Meridional and vertical velocities are smaller and peak at lower altitudes during early transitions (20–30 days prior to solstice) than is the case for late transitions that occur at solstice or later.

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confidence: 77%

Trends and Variability in Vertical Winds in the Southern Hemisphere Summer Polar Mesosphere and Lower Thermosphere

et al. 2019

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“…With global coverage (48°S to 48°N), the trend based on Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on board the Thermosphere Ionosphere Mesosphere and Dynamics temperatures (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012) was published (Huang et al, 2014). A later report (Holmen et al, 2016) based on the same technique at a similar latitude (Tromso, 70N) between 2003 and 2014, however, reported trend of −2.2 ± 1.0 K/decade. These SABER results are compared to the most recent lidar results later in this paper.…”

Section: Introductionmentioning

confidence: 99%

Solar Response and Long‐Term Trend of Midlatitude Mesopause Region Temperature Based on 28 Years (1990–2017) of Na Lidar Observations

et al. 2019

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We present midlatitude solar response and linear trend from Colorado State University/Utah State University Na lidar nocturnal temperature observations between 1990 and 2017. Along with the nightly mean temperatures (_Ngt), we also use the corresponding 2‐hr means centered at midnight (_2MN), resulting in vertical trend profiles similar in shapes as those previously published. The 28‐year trend from _Ngt (_2MN) data set starts from a small warming at 85 km, to cooling at 87 (88) km, reaching a maximum of 1.85 ± 0.53 (1.09 ± 0.74) at 92 (93) km and turns positive again at 102 (100) km. The 6‐month winter trend is much cooler than the 4‐month summer trend with comparable solar response varying around 5 ± 1 K/100 SFU throughout the profile (85–105 km) with higher summer values. We explore the observed summer/winter trend difference in terms of observed gravity wave heat flux heating rate at a nearby station and the long‐term trend of gravity wave variance at a midlatitude. Between 89 and 100 km, the lidar trends are within the error bars of the Leibniz Middle Atmosphere (LIMA) summer trends (1979–2013), which are nearly identical to the lidar‐Ngt trend. We address the need of long data set for reliable analysis on trend, the extent of trend uncertainty due to possible tidal bias, the effect of a Pinatubo/episodic function, and the impact of stratospheric ozone recovery.

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“…Meteor radar techniques are widely used for studying the dynamics and climate of the MLT region, including wind fields, temperature, and density (e.g., Cervera & Reid, 2000;Chilson et al, 1996;Hall et al, 2006Hall et al, , 2012Hocking, 1999;Hocking, Thayaparan, & Jones, 1997;Hocking et al, 2004;Holdsworth, Reid, & Cervera, 2004;Holdsworth et al, 2006;Holmen et al, 2016;Kumar, 2007;Lee et al, 2016;Liu et al, 2017;Neilsen et al, 2001;Singer, Bremer, et al, 2004;Singer et al, 2003;Stober et al, 2008Stober et al, , 2012Stober et al, , 2014Takahashi et al, 2002;Tsutsumi et al, 1994;Yi et al, 2016;Younger et al, 2015). The peak of the height distribution of meteor radar detections can be used to estimate neutral atmospheric density variations in the MLT region (e.g., Clemesha & Batista, 2006;Lima et al, 2015;Stober et al, 2012Stober et al, , 2014Yi, Reid, Xue, Younger, Spargo, et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Estimation of Mesospheric Densities at Low Latitudes Using the Kunming Meteor Radar Together With SABER Temperatures

Xue

Younger

et al. 2018

JGR Space Physics

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Neutral mesospheric densities at a low latitude have been derived during April 2011 to December 2014 using data from the Kunming meteor radar in China (25.6°N, 103.8°E). The daily mean density at 90 km was estimated using the ambipolar diffusion coefficients from the meteor radar and temperatures from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument. The seasonal variations of the meteor radar‐derived density are consistent with the density from the Mass Spectrometer and Incoherent Scatter (MSIS) model, show a dominant annual variation, with a maximum during winter, and a minimum during summer. A simple linear model was used to separate the effects of atmospheric density and the meteor velocity on the meteor radar peak detection height. We find that a 1 km/s difference in the vertical meteor velocity yields a change of approximately 0.42 km in peak height. The strong correlation between the meteor radar density and the velocity‐corrected peak height indicates that the meteor radar density estimates accurately reflect changes in neutral atmospheric density and that meteor peak detection heights, when adjusted for meteoroid velocity, can serve as a convenient tool for measuring density variations around the mesopause. A comparison of the ambipolar diffusion coefficient and peak height observed simultaneously by two co‐located meteor radars indicates that the relative errors of the daily mean ambipolar diffusion coefficient and peak height should be less than 5% and 6%, respectively, and that the absolute error of the peak height is less than 0.2 km.

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Neutral atmosphere temperature trends and variability at 90 km, 70 °N, 19 °E, 2003–2014

Abstract: Abstract. Neutral temperatures at 90 km height above Tromsø, Norway, have been determined using ambipolar diffusion coefficients calculated from meteor echo fading times using the Nippon/Norway Tromsø Meteor Radar (NTMR).

Cited by 21 publications

References 59 publications

Trends and Variability in Vertical Winds in the Southern Hemisphere Summer Polar Mesosphere and Lower Thermosphere

Trends and Variability in Vertical Winds in the Southern Hemisphere Summer Polar Mesosphere and Lower Thermosphere

Solar Response and Long‐Term Trend of Midlatitude Mesopause Region Temperature Based on 28 Years (1990–2017) of Na Lidar Observations

Estimation of Mesospheric Densities at Low Latitudes Using the Kunming Meteor Radar Together With SABER Temperatures

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Neutral atmosphere temperature trends and variability at 90 km, 70 °N, 19 °E, 2003–2014

Abstract: Abstract. Neutral temperatures at 90 km height above Tromsø, Norway, have been determined using ambipolar diffusion coefficients calculated from meteor echo fading times using the Nippon/Norway Tromsø Meteor Radar (NTMR).

Cited by 21 publications

References 59 publications

Trends and Variability in Vertical Winds in the Southern Hemisphere Summer Polar Mesosphere and Lower Thermosphere

Trends and Variability in Vertical Winds in the Southern Hemisphere Summer Polar Mesosphere and Lower Thermosphere

Solar Response and Long‐Term Trend of Midlatitude Mesopause Region Temperature Based on 28 Years (1990–2017) of Na Lidar Observations

Estimation of Mesospheric Densities at Low Latitudes Using the Kunming Meteor Radar Together With SABER Temperatures

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Neutral atmosphere temperature trends and variability at 90 km, 70 °N, 19 °E, 2003–2014