Evaluation of the Mesospheric Polar Vortices in WACCM

Harvey, V. Lynn; Randall, C. E.; Becker, Erich; Smith, Anne K.; Bardeen, Charles G.; Гончаренко, Л. П.

doi:10.1029/2019jd030727

Cited by 17 publications

(29 citation statements)

References 126 publications

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“…However, there are important quantitative differences among the DJF zonal mean temperature distributions, most notably in the tropics from 80 to 100 km altitude, where WACCMX+DART produces temperatures that are > 20 K warmer than corresponding temperatures produced by the NAVGEM-HA and JAGUAR-DAS systems. A warm bias at the tropical mesopause has been documented previously in free-running WACCM model simulations (e.g., Smith, 2012;Marsh et al, 2013;Harvey et al, 2019), but the cause is not yet fully understood. We also note that the summer polar temperature at 80 km altitude is ∼ 20 K colder in WACCMX+DART compared to the other three data sets.…”

Section: Zonal Mean Resultsmentioning

confidence: 79%

Intercomparison of middle atmospheric meteorological analyses for the Northern Hemisphere winter 2009–2010

et al. 2021

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Abstract. Detailed meteorological analyses based on observations extending through the middle atmosphere (∼ 15 to 100 km altitude) can provide key information to whole atmosphere modeling systems regarding the physical mechanisms linking day-to-day changes in ionospheric electron density to meteorological variability near the Earth's surface. However, the extent to which independent middle atmosphere analyses differ in their representation of wave-induced coupling to the ionosphere is unclear. To begin to address this issue, we present the first intercomparison among four such analyses, JAGUAR-DAS, MERRA-2, NAVGEM-HA, and WACCMX+DART, focusing on the Northern Hemisphere (NH) 2009–2010 winter, which includes a major sudden stratospheric warming (SSW). This intercomparison examines the altitude, latitude, and time dependences of zonal mean zonal winds and temperatures among these four analyses over the 1 December 2009 to 31 March 2010 period, as well as latitude and altitude dependences of monthly mean amplitudes of the diurnal and semidiurnal migrating solar tides, the eastward-propagating diurnal zonal wave number 3 nonmigrating tide, and traveling planetary waves associated with the quasi-5 d and quasi-2 d Rossby modes. Our results show generally good agreement among the four analyses up to the stratopause (∼ 50 km altitude). Large discrepancies begin to emerge in the mesosphere and lower thermosphere owing to (1) differences in the types of satellite data assimilated by each system and (2) differences in the details of the global atmospheric models used by each analysis system. The results of this intercomparison provide initial estimates of uncertainty in analyses commonly used to constrain middle atmospheric meteorological variability in whole atmosphere model simulations.

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Section: Zonal Mean Resultsmentioning

confidence: 79%

Intercomparison of middle atmospheric meteorological analyses for the Northern Hemisphere winter 2009–2010

et al. 2021

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“…km altitude, where WACCMX+DART produces temperatures that are >20 K warmer than corresponding temperatures produced by the NAVGEM-HA and JAGUAR-DAS systems. A warm bias at the tropical mesopause has been previously documented in free-running WACCM model simulations (e.g., Smith, 2012;Marsh et al, 2013;Harvey et al, 2019) but the cause is not yet fully understood. We also note that the summer polar temperature at 80 km altitude is ~20 K colder in WACCMX+DART compared to the other three data sets.…”

Section: Zonal Mean Resultsmentioning

confidence: 98%

Intercomparison of Middle Atmospheric Meteorological Analyses for the Northern Hemisphere Winter 2009–2010

McCormack

Harvey

Pedatella

et al. 2021

Preprint

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Abstract. Detailed meteorological analyses based on observations extending through the middle atmosphere (~15–100 km altitude) can provide key information to whole atmosphere modelling systems regarding the physical mechanisms linking day-to-day changes in ionospheric electron density to meteorological variability near the Earth’s surface. It is currently unclear how middle atmosphere analyses produced by various research groups consistently represent the wide range of proposed linking mechanisms involving migrating and non-migrating tides, planetary waves, gravity waves, and their impact on the zonal mean state in the mesosphere and lower thermosphere (MLT) region. To begin to address this issue, we present the first intercomparison among four such analyses, JAGUAR-DAS, MERRA-2, NAVGEM-HA, and WACCMX+DART, focusing on the Northern Hemisphere (NH) 2009–2010 winter that includes a major stratospheric sudden warming (SSW) in late January. This intercomparison examines the altitude, latitude, and time dependences of zonal mean zonal winds and temperatures among these four analyses over the 1 December 2009–31 March 2010 period, as well as latitude and altitude dependences of monthly mean amplitudes of the diurnal and semidiurnal migrating solar tides, the eastward propagating diurnal zonal wave number 3 nonmigrating tide, and traveling planetary waves associated with the quasi-5 day and quasi-2-day Rossby modes. Our results show generally good agreement among the four analyses up to the stratopause (~50 km altitude). Large discrepancies begin to emerge in the MLT owing to (1) differences in the types of satellite data assimilated by each system and (2) differences in the details of the global atmospheric models used by each analysis system. The results of this intercomparison provide initial estimates of uncertainty in analyses commonly used to constrain middle atmospheric meteorological variability in whole atmosphere model simulations.

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“…Westward wintertime winds in the simulated polar MLT are a long-standing feature of WACCM (Harvey et al, 2019;Ramesh et al, 2020;Stober et al, 2021b), and they are also found in the thermospheric extension WACCM-X (Liu et al, 2010;Pedatella et al, 2014;Liu et al, 2018;Pancheva et al, 2020) and in other high-top models such as the MUAM (Lilienthal et al, 2018).…”

Section: Secondary Gws and Differences Between Radar Observations And Waccmmentioning

confidence: 79%

“…This difference is well-known (e.g. Smith, 2012;Harvey et al, 2019) and may be considered as one of the most significant biases in numerical simulations of the MLT with important impacts for MLT chemistry. There is a growing body of literature that suggests that this reversal of the modelled zonal winds could be due to an incomplete representation of drag due to GWs, in particular secondary GWs Becker and Vadas, 2018;.…”

Section: Comparison Of Radar Winds and Satellite Temperatures To Waccmmentioning

confidence: 98%

“…Radar and satellite observations indicate that the wintertime winds are eastward throughout the MLT at high latitudes during winter, forming part of a mesospheric extension of the eastward stratospheric polar vortex (e.g. Beldon and Mitchell, 2009;Harvey et al, 2019). In WACCM, the zonal winds decelerate and eventually reverse to westward above 85 km altitude throughout April to September.…”

Section: Comparison Of Radar Winds and Satellite Temperatures To Waccmmentioning

confidence: 99%

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Radar observations of winds, waves and tides in the mesosphere and lower thermosphere over South Georgia island (54°S, 36°W) and comparison to WACCM simulations

Hindley

Cobbett

Fritts

et al. 2021

Preprint

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Abstract. The mesosphere and lower thermosphere (MLT) is a dynamic layer of the earth’s atmosphere. This region marks the interface at which neutral atmosphere dynamics begin to influence the ionosphere and space weather. However, our understanding of this region and our ability to accurately simulate it in global circulation models (GCMs) is limited by a lack of observations, especially in remote locations. To this end, a meteor radar was deployed on the remote mountainous island of South Georgia (54° S, 36° W) in the Southern Ocean from 2016 to 2020. The goal of this study is to use these new measurements to characterise the fundamental dynamics of the MLT above South Georgia including large-scale winds, solar tides, planetary waves (PWs) and mesoscale gravity waves (GWs). We first present an improved method for time-height localisation of radar wind measurements and characterise the large-scale MLT winds. We then explore the amplitudes and phases of the diurnal (24 h), semidiurnal (12 h) and terdiurnal (8 h) solar tides at this latitude. We also explore PW activity and find very large amplitudes up to 30 ms−1 for the quasi-2 day wave in summer and show that the dominant modes of the quasi-5, 10 and 16 day waves are westward W1 and W2. We investigate wind variance due to GWs in the MLT and use a new method to show an east-west tendency of GW variance of up to 20 % during summer and a weaker north-south tendency of 0–5 % during winter. This is contrary to the expected tendency of GW directions in the winter stratosphere below, which is a strong suggestion of secondary GW (2GW) observations in the MLT. Lastly, comparison of radar winds to a climatological Whole Atmosphere Community Climate Model (WACCM) simulation reveals a simulated summertime mesopause and zonal wind shear that occur at altitudes around 10 km lower than observed, and southward winds during winter above 90 km altitude in the model that are not seen in observations. Further, wintertime zonal winds above 85 km altitude are eastward in radar observations but in WACCM they are found to weaken and reverse to westward. Recent studies have linked this discrepancy to the impact of 2GWs on the residual circulation which are not included in WACCM. These measurements therefore provide vital constraints that can guide the development of GCMs as they extend upwards into this important region of the atmosphere.

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Evaluation of the Mesospheric Polar Vortices in WACCM

Cited by 17 publications

References 126 publications

Intercomparison of middle atmospheric meteorological analyses for the Northern Hemisphere winter 2009–2010

Intercomparison of middle atmospheric meteorological analyses for the Northern Hemisphere winter 2009–2010

Intercomparison of Middle Atmospheric Meteorological Analyses for the Northern Hemisphere Winter 2009–2010

Radar observations of winds, waves and tides in the mesosphere and lower thermosphere over South Georgia island (54°S, 36°W) and comparison to WACCM simulations

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