The influence of major sudden stratospheric warming and elevated stratopause events on the effects of energetic particle precipitation in WACCM

Holt, Laura; Randall, C. E.; Peck, E. D.; Marsh, Daniel R.; Smith, Anne K.; Harvey, V. Lynn

doi:10.1002/2013jd020294

Cited by 50 publications

(70 citation statements)

References 38 publications

(56 reference statements)

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“…Moreover, this figure shows that the tongue of dry air observed by SMR extended at least 5 km lower in the stratosphere in 2013 than in 2009. These results are perfectly consistent with the study carried out by Holt et al (2013), which showed that the earlier a SSW event occurs in the winter season, and the stronger is the descent following the event.…”

Section: Middle Atmospheric Dynamical Activitysupporting

confidence: 93%

“…The differences between these two winters can be explained by the earlier onset of the dynamical event in 2013 compared to 2009. Holt et al (2013) indeed showed that the EPP indirect effect is larger for earlier central warming dates for two main reasons: the earlier an event occurs in the winter season, the stronger is the following descent, and the longer the EPP-NO x can be transported down before the final warming occurs. This highlights the importance of the dynamics for the EPP IE.…”

Section: K Pérot Et Al: 2013 Arctic No In Odin/smr Data 3 Summary Amentioning

confidence: 93%

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Unusually strong nitric oxide descent in the Arctic middle atmosphere in early 2013 as observed by Odin/SMR

2014

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Abstract. The middle atmosphere was affected by an exceptionally strong midwinter stratospheric sudden warming (SSW) during the Arctic winter 2012/2013. These unusual meteorological conditions led to a breakdown of the polar vortex, followed by the reformation of a strong upper stratospheric vortex associated with particularly efficient descent of air. Measurements by the submillimetre radiometer (SMR), on board the Odin satellite, show that very large amounts of nitric oxide (NO), produced by energetic particle precipitation (EPP) in the mesosphere/lower thermosphere (MLT), could thus enter the polar stratosphere in early 2013. The mechanism referring to the downward transport of EPP-generated NO x during winter is generally called the EPP indirect effect. SMR observed up to 20 times more NO in the upper stratosphere than the average NO measured at the same latitude, pressure and time during three previous winters where no mixing between mesospheric and stratospheric air was noticeable. This event turned out to be the strongest in the aeronomy-only period of SMR (2007-present). Our study is based on a comparison with the Arctic winter 2008/2009, when a similar situation was observed. This outstanding situation is the result of the combination of a relatively high geomagnetic activity and an unusually high dynamical activity, which makes this case a prime example to study the EPP impacts on the atmospheric composition.

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Section: Middle Atmospheric Dynamical Activitysupporting

confidence: 93%

Section: K Pérot Et Al: 2013 Arctic No In Odin/smr Data 3 Summary Amentioning

confidence: 93%

Unusually strong nitric oxide descent in the Arctic middle atmosphere in early 2013 as observed by Odin/SMR

2014

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“…Interannual variations of the EPP-NO y seasonal dependence, driven by variations of chemical losses and transport patterns, are not considered in the standard mode of the UBC model. Optionally, episodes of accelerated descent associated with elevated stratopause (ES) events in Arctic winters can be considered by means of a dedicated parameterization, taking into account the dependence of the EPP-NO y amounts and fluxes on the event timing (Holt et al, 2013). Although its application is recommended in principle, we note that it requires the implementation of the UBC model into the climate model system since ES events cannot be predicted in free-running model simulations.…”

Section: The Epp Indirect Effect: Odd Nitrogen Upper-boundary Conditionmentioning

confidence: 99%

Solar forcing for CMIP6 (v3.2)

et al. 2017

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Abstract. This paper describes the recommended solar forcing dataset for CMIP6 and highlights changes with respect to CMIP5. The solar forcing is provided for radiative properties, namely total solar irradiance (TSI), solar spectral irradiance (SSI), and the F10.7 index as well as particle forcing, including geomagnetic indices Ap and Kp, and ionization rates to account for effects of solar protons, electrons, and galactic cosmic rays. This is the first time that a recommendation for solar-driven particle forcing has been provided for a CMIP exercise. The solar forcing datasets are provided at daily and monthly resolution separately for the CMIP6 preindustrial control, historical (1850CMIP6 preindustrial control, historical ( -2014, and future (2015-2300) simulations. For the preindustrial control simulation, both constant and time-varying solar forcing components are provided, with the latter including variability on 11-year and shorter timescales but no long-term changes. For the future, we provide a realistic scenario of what solar behavior could be, as well as an additional extreme Maunderminimum-like sensitivity scenario. This paper describes the forcing datasets and also provides detailed recommendations as to their implementation in current climate models.For the historical simulations, the TSI and SSI time series are defined as the average of two solar irradiance models that are adapted to CMIP6 needs: an empirical onePublished by Copernicus Publications on behalf of the European Geosciences Union. A new and lower TSI value is recommended: the contemporary solar-cycle average is now 1361.0 W m −2 . The slight negative trend in TSI over the three most recent solar cycles in the CMIP6 dataset leads to only a small global radiative forcing of −0.04 W m −2 . In the 200-400 nm wavelength range, which is important for ozone photochemistry, the CMIP6 solar forcing dataset shows a larger solar-cycle variability contribution to TSI than in CMIP5 (50 % compared to 35 %).We compare the climatic effects of the CMIP6 solar forcing dataset to its CMIP5 predecessor by using timeslice experiments of two chemistry-climate models and a reference radiative transfer model. The differences in the long-term mean SSI in the CMIP6 dataset, compared to CMIP5, impact on climatological stratospheric conditions (lower shortwave heating rates of −0.35 K day −1 at the stratopause), cooler stratospheric temperatures (−1.5 K in the upper stratosphere), lower ozone abundances in the lower stratosphere (−3 %), and higher ozone abundances (+1.5 % in the upper stratosphere and lower mesosphere). Between the maximum and minimum phases of the 11-year solar cycle, there is an increase in shortwave heating rates (+0.2 K day −1 at the stratopause), temperatures (∼ 1 K at the stratopause), and ozone (+2.5 % in the upper stratosphere) in the tropical upper stratosphere using the CMIP6 forcing dataset. This solar-cycle response is slightly larger, but not statistically significantly different from that for the CMIP5 forcing dataset.CMIP6 models wi...

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“…Periods of strong atmospheric descent are known to coincide with the timing of sudden stratospheric warmings (SSWs; e.g. Manney et al, 2003Manney et al, , 2009Jackman et al, 2009;Siskind et al, 2010;Holt et al, 2013). Elevated VMRs of carbon monoxide (CO) and NO x have been observed to linger in the middle atmosphere when there is an exceptionally strong polar vortex after a strong SSW, helping to confine descending air at the pole (Randall et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Assessing the ability to derive rates of polar middle-atmospheric descent using trace gas measurements from remote sensors

et al. 2018

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Abstract. We investigate the reliability of using trace gas measurements from remote sensing instruments to infer polar atmospheric descent rates during winter within 46-86 km altitude. Using output from the Specified Dynamics Whole Atmosphere Community Climate Model (SD-WACCM) between 2008 and 2014, tendencies of carbon monoxide (CO) volume mixing ratios (VMRs) are used to assess a common assumption of dominant vertical advection of tracers during polar winter. The results show that dynamical processes other than vertical advection are not negligible, meaning that the transport rates derived from trace gas measurements do not represent the mean descent of the atmosphere. The relative importance of vertical advection is lessened, and exceeded by other processes, during periods directly before and after a sudden stratospheric warming, mainly due to an increase in eddy transport. It was also found that CO chemistry cannot be ignored in the mesosphere due to the night-time layer of OH at approximately 80 km altitude. CO VMR profiles from the Kiruna Microwave Radiometer and the Microwave Limb Sounder were compared to SD-WACCM output, and show good agreement on daily and seasonal timescales. SD-WACCM CO profiles are combined with the CO tendencies to estimate errors involved in calculating the mean descent of the atmosphere from remote sensing measurements. The results indicate errors on the same scale as the calculated descent rates, and that the method is prone to a misinterpretation of the direction of air motion. The "true" rate of atmospheric descent is seen to be masked by processes, other than vertical advection, that affect CO. We suggest an alternative definition of the rate calculated using remote sensing measurements: not as the mean descent of the atmosphere, but as an effective rate of vertical transport for the trace gas under observation.

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The influence of major sudden stratospheric warming and elevated stratopause events on the effects of energetic particle precipitation in WACCM

Cited by 50 publications

References 38 publications

Unusually strong nitric oxide descent in the Arctic middle atmosphere in early 2013 as observed by Odin/SMR

Unusually strong nitric oxide descent in the Arctic middle atmosphere in early 2013 as observed by Odin/SMR

Solar forcing for CMIP6 (v3.2)

Assessing the ability to derive rates of polar middle-atmospheric descent using trace gas measurements from remote sensors

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