Occurrence of Winter Stratospheric Sudden Warming Events and the Seasonal Timing of Spring Stratospheric Final Warming

Hu, Jinggao; Ren, Rongcai; Xu, Haiming

doi:10.1175/jas-d-13-0349.1

Cited by 101 publications

(129 citation statements)

References 42 publications

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“…Gerber and Polvani (2009) explicitly demonstrated a realistic tropospheric signal associated with SSWs in their global model. FWs are also observed to have a similar tropospheric impact, although its latitudinal structure differs somewhat from the annular-mode form (Black et al 2006;Black and McDaniel 2007a,b;Hu et al 2014b), and uppertropospheric planetary-scale waves may play a role (Sun et al 2011). Similar results have been found in simplified global models (Sun and Robinson 2009;Sun et al 2011;Sheshadri et al 2014).…”

Section: Introductionsupporting

confidence: 54%

“…Both the cases with 3000-and 4000-m wave-2 topography result in weak easterlies following the final warming. Hu et al (2014a), in their analysis of the timing of midwinter warming events and final warming events in the NCEP-NCAR reanalysis, suggested that late spring final warming events tend to be preceded by major SSWs, while early FW events do not. Similarly, in experiment 4, we find that final warming events occur on average 11 days later in years with major SSW events.…”

Section: B Final Warming Eventsmentioning

confidence: 99%

“…Similar final warmings (FWs), which occur at the end of winter at the final transition into the summertime circulation, occur in both hemispheres. These events show many similarities to SSWs, especially in being characterized by planetary wave amplification; their timing is variable around or after the spring equinox (being delayed by around 2 months with respect to equinox in the Southern Hemisphere), with the early events being the most active (Black and McDaniel 2007a,b;Hu et al 2014b).…”

Section: Introductionmentioning

confidence: 99%

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Seasonal Variability of the Polar Stratospheric Vortex in an Idealized AGCM with Varying Tropospheric Wave Forcing

Sheshadri

Plumb

Gerber

2015

Journal of the Atmospheric Sciences

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The seasonal variability of the polar stratospheric vortex is studied in a simplified AGCM driven by specified equilibrium temperature distributions. Seasonal variations in equilibrium temperature are imposed in the stratosphere only, enabling the study of stratosphere-troposphere coupling on seasonal time scales, without the complication of an internal tropospheric seasonal cycle. The model is forced with different shapes and amplitudes of simple bottom topography, resulting in a range of stratospheric climates. The effect of these different kinds of topography on the seasonal variability of the strength of the polar vortex, the average timing and variability in timing of the final breakup of the vortex (final warming events), the conditions of occurrence and frequency of midwinter warming events, and the impact of the stratospheric seasonal cycle on the troposphere are explored. The inclusion of wavenumber-1 and wavenumber-2 topographies results in very different stratospheric seasonal variability. Hemispheric differences in stratospheric seasonal variability are recovered in the model with appropriate choices of wave-2 topography. In the model experiment with a realistic Northern Hemisphere-like frequency of midwinter warming events, the distribution of the intervals between these events suggests that the model has no year-to-year memory. When forced with wave-1 topography, the gross features of seasonal variability are similar to those forced with wave-2 topography, but the dependence on forcing magnitude is weaker. Further, the frequency of major warming events has a nonmonotonic dependence on forcing magnitude and never reaches the frequency observed in the Northern Hemisphere.

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Section: Introductionsupporting

confidence: 54%

Section: B Final Warming Eventsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Seasonal Variability of the Polar Stratospheric Vortex in an Idealized AGCM with Varying Tropospheric Wave Forcing

Sheshadri

Plumb

Gerber

2015

Journal of the Atmospheric Sciences

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“…A total of 12 and 10 SSW events are categorized as Type-1 and Type-25 2, respectively. Hu et al (2014) identified and categorized the SSW events in 55 years of NCEP-NCAR data based on the criteria of CP07. Compared to Hu et al (2014), four SSW events were categorized as different types (the Dec. 1998, Feb. 1999, Jan. 2006, and Feb. 2007.…”

Section: Statistics Of Ssw Events Revealed In Reanalysis Data Sets 20mentioning

confidence: 99%

Residual Mean Circulation and Temperature Changes during the Evolution of Stratospheric Sudden Warming Revealed in MERRA

Song

Chun

2016

Preprint

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Abstract.Residual mean circulation and temperature changes during the evolution of major stratospheric sudden warming (SSW) are investigated by composite analyses of 22 SSW events from 1979 to 2012 during the Northern Hemisphere winter (November-March) using four reanalysis data sets (MERRA, ERA-Interim, NCEP-NCAR, and JRA-55). The SSW events are classified as Type-1 or Type-2 based on the relative amplitude of planetary waves with zonal wavenumbers 1 and 2. The residual mean circulation induced by each forcing term in the Transformed Eulerian mean (TEM) momentum equation and 10 the temperature advection associated with the circulation are calculated for both types of SSW, based on the generalized downward control principle using the MERRA data set. When 'Lag = 0' is defined as the day on which the wind reversal occurred at 60° N and 10 hPa, strong poleward and downward motion exists at Lag = -8 and Lag = -1 for Type-1 and at Lag = -3 for Type-2, which is induced primarily by the Eliassen-Palm flux divergence forcing (EPD). The poleward and downward motion is stronger for Type-2 than for Type-1. Gravity wave drag (GWD) produces a smaller contribution to the 15 residual circulation than EPD. During the warming phase (at Lag = -2), strong temperature advection by the EPD induces primarily polar stratospheric warming. On the other hand, during the temperature recovery phase (at Lag = +2), anomalous negative temperature advection and diabatic cooling produce negative temperature tendency anomalies. Structures in the temperature tendency and temperature advection calculated using the MERRA data set are similar to those calculated using the ERA-Interim data set. 20

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“…It has long been recognized that the winter to spring transition is characterized by a decay and breakdown of the wintertime westerly jet and its eventual replacement by a zonal mean easterly flow around the polar region. This is known as the stratospheric final warming (SFW) (Hu et al, 2014). It has been observed that certain remnants of wintertime dynamical (Hess, 1990) or chemical tracer features (Orsolini, 2001;Lahoz et al, 2007) can persist well into the summer season.…”

Section: Introductionmentioning

confidence: 99%

Persistence of upper stratospheric wintertime tracer variability into the Arctic spring and summer

et al. 2016

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Abstract. Using data from the Aeronomy of Ice in the Mesosphere (AIM) and Aura satellites, we have categorized the interannual variability of winter-and springtime upper stratospheric methane (CH 4 ). We further show the effects of this variability on the chemistry of the upper stratosphere throughout the following summer. Years with strong wintertime mesospheric descent followed by dynamically quiet springs, such as 2009, lead to the lowest summertime CH 4 . Years with relatively weak wintertime descent, but strong springtime planetary wave activity, such as 2011, have the highest summertime CH 4 . By sampling the Aura Microwave Limb Sounder (MLS) according to the occultation pattern of the AIM Solar Occultation for Ice Experiment (SOFIE), we show that summertime upper stratospheric chlorine monoxide (ClO) almost perfectly anticorrelates with the CH 4 . This is consistent with the reaction of atomic chlorine with CH 4 to form the reservoir species, hydrochloric acid (HCl). The summertime ClO for years with strong, uninterrupted mesospheric descent is about 50 % greater than in years with strong horizontal transport and mixing of high CH 4 air from lower latitudes. Small, but persistent effects on ozone are also seen such that between 1 and 2 hPa, ozone is about 4-5 % higher in summer for the years with the highest CH 4 relative to the lowest. This is consistent with the role of the chlorine catalytic cycle on ozone. These dependencies may offer a means to monitor dynamical effects on the high-latitude upper stratosphere using summertime ClO measurements as a proxy. Additionally, these chlorine-controlled ozone decreases, which are seen to maximize after years with strong uninterrupted wintertime descent, represent a new mechanism by which mesospheric descent can affect polar ozone. Finally, given that the effects on ozone appear to persist much of the rest of the year, the consideration of winter/spring dynamical variability may also be relevant in studies of ozone trends.

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Occurrence of Winter Stratospheric Sudden Warming Events and the Seasonal Timing of Spring Stratospheric Final Warming

Cited by 101 publications

References 42 publications

Seasonal Variability of the Polar Stratospheric Vortex in an Idealized AGCM with Varying Tropospheric Wave Forcing

Seasonal Variability of the Polar Stratospheric Vortex in an Idealized AGCM with Varying Tropospheric Wave Forcing

Residual Mean Circulation and Temperature Changes during the Evolution of Stratospheric Sudden Warming Revealed in MERRA

Persistence of upper stratospheric wintertime tracer variability into the Arctic spring and summer

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