The anomalous change in the QBO in 2015–2016

Newman, Paul A.; Coy, L.; Pawson, Steven; Lait, Leslie R.

doi:10.1002/2016gl070373

Cited by 175 publications

(220 citation statements)

References 17 publications

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“…A crucial test of our understanding and ability to model the QBO occurred around the beginning of 2016 when the QBO cycle was unexpectedly disrupted for the first time since its discovery in the late 1950s (Dunkerton, 2016;Newman et al, 2016;Osprey et al, 2016;Coy et al, 2017). The well-established QBO paradigm, originating from the 1960s, of alternate eastward and westward momentum deposition from vertically propagating equatorial waves (Baldwin et al, 2001) could not account for this disruption .…”

Section: Scientific Rationalementioning

confidence: 99%

Overview of experiment design and comparison of models participating in phase 1 of the SPARC Quasi-Biennial Oscillation initiative (QBOi)

Anstey²,

et al. 2018

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Abstract. The Stratosphere-troposphere Processes And their Role in Climate (SPARC) Quasi-Biennial Oscillation initiative (QBOi) aims to improve the fidelity of tropical stratospheric variability in general circulation and Earth system models by conducting coordinated numerical experiments and analysis. In the equatorial stratosphere, the QBO is the most conspicuous mode of variability. Five coordinated experiments have therefore been designed to (i) evaluate and compare the verisimilitude of modelled QBOs under presentday conditions, (ii) identify robustness (or alternatively the spread and uncertainty) in the simulated QBO response to commonly imposed changes in model climate forcings (e.g. a doubling of CO 2 amounts), and (iii) examine model dependence of QBO predictability. This paper documents these experiments and the recommended output diagnostics. The rationale behind the experimental design and choice of diagnostics is presented. To facilitate scientific interpretation of the results in other planned QBOi studies, consistent descriptions of the models performing each experiment set are given, with those aspects particularly relevant for simulating the QBO tabulated for easy comparison.

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Section: Scientific Rationalementioning

confidence: 99%

Overview of experiment design and comparison of models participating in phase 1 of the SPARC Quasi-Biennial Oscillation initiative (QBOi)

Anstey²,

et al. 2018

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“…The unusual disruption of the QBO in winter 2015/2016, characterized by anomalous easterly acceleration occurring in the QBO westerlies (e.g., Osprey et al, 2016;Newman et al, 2016;Coy et al, 2017), begins at approximately the same time as the unusual strong SPW amplitude takes place in the subtropical mesosphere. Osprey et al (2016) found an anomalous easterly acceleration of the equatorial winds at 40 hPa (approx.…”

Section: Why Does the Spw 2 Dominate In Period Ii?mentioning

confidence: 99%

“…Firstly, in early winter the polar vortex was the coldest and strongest it has been in 68 years (Matthias et al, 2016) with zonal mean wind speeds of over 80 m s −1 around the stratopause in midlatitudes. Secondly, a significant disruption of the quasibiennial oscillation (QBO) occurred, beginning at the end of December 2015 and fully completing by mid-April 2016 (Osprey et al, 2016;Newman et al, 2016;Coy et al, 2017). Thirdly, this particular winter was also characterized by one of the strongest El Niño events on record, with a strong polar stratospheric signature (Palmeiro et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

On the origin of the mesospheric quasi-stationary planetary waves in the unusual Arctic winter 2015/2016

Matthias

Ern²

2018

Atmos. Chem. Phys.

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Abstract. The midwinter 2015/2016 was characterized by an unusually strong polar night jet (PNJ) and extraordinarily large stationary planetary wave (SPW) amplitudes in the subtropical mesosphere. The aim of this study is, therefore, to find the origin of these mesospheric SPWs in the midwinter 2015/2016 study period. The study duration is split into two periods: the first period runs from late December 2015 until early January 2016 (Period I), and the second period from early January until mid-January 2016 (Period II). While the SPW 1 dominates in the subtropical mesosphere in Period I, it is the SPW 2 that dominates in Period II. There are three possibilities explaining how SPWs can occur in the mesosphere: (1) they propagate upward from the stratosphere, (2) they are generated in situ by longitudinally variable gravity wave (GW) drag, or (3) they are generated in situ by barotropic and/or baroclinic instabilities. Using global satellite observations from the Microwave Limb Sounder (MLS) and the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) the origin of the mesospheric SPWs is investigated for both time periods. We find that due to the strong PNJ the SPWs were not able to propagate upward into the mesosphere northward of 50 • N but were deflected upward and equatorward into the subtropical mesosphere. We show that the SPWs observed in the subtropical mesosphere are the same SPWs as in the mid-latitudinal stratosphere. Simultaneously, we find evidence that the mesospheric SPWs in polar latitudes were generated in situ by longitudinally variable GW drag and that there is a mixture of in situ generation by longitudinally variable GW drag and by instabilities at mid-latitudes. Our results, based on observations, show that the abovementioned three mechanisms can act at the same time which confirms earlier model studies. Additionally, the possible contribution from, or impact of, unusually strong SPWs in the subtropical mesosphere to the disruption of the quasi-biennial oscillation (QBO) in the same winter is discussed.

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“…However, the stacked easterlies/westerlies/easterlies observed at Kiritimati (Fig. 9a) and at Singapore (Newman et al 2016) are clearly 10 present in early-to mid-March 2016 (Fig. 9b), and fine-scale descending waves are evident in the lower stratosphere above about 20 km through much of the cruise (Fig.…”

Section: Soundings From Kiritimati Islandmentioning

confidence: 99%

Ship- and island-based soundings from the 2016 El Niño Rapid Response (ENRR) field campaign

Hartten¹,

Cox²,

Johnston³

et al. 2018

Preprint

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Abstract. As the 2015/2016 El Niño was gathering strength in late 2015, scientists at the Earth System Research Laboratory's Physical Sciences Division proposed and led the implementation of NOAA's El Niño Rapid Response (ENRR) Field Campaign. ENRR observations included wind and thermodynamic profiles of the atmosphere over the near-equatorial east-central Pacific Ocean, many of which were collected from two field sites and transmitted in near-real time for inclusion in global forecasting models. From 26 January to 28 March 2016, twice-daily rawinsonde observations were made from Kiritimati (pronounced Christmas) Island (2.0°N, 157.4°E; call sign CXENRR). From 16 February to 16 March 2016, three to eight radiosondes were launched each day from the NOAA Ship Ronald H. Brown (allocated call sign WTEC) as it travelled southeast from Hawaii to service Tropical Atmosphere Ocean (TAO) buoys along longitudes 140°W and 125°W and then north to San Diego, California. Both the rapid and the remote nature of these deployments created particular difficulties in collecting and disseminating the soundings; these are described together with the methods used to reprocess the data after the field campaign finished. The reprocessed and lightly quality-controlled data have been put into an easy-to-read text format, qualifying them to be termed Level 2 soundings. They are archived and freely available for public access at NOAA's National Centers for Environmental Information (NCEI) in the form of two separate data sets: one consisting of 125 soundings from Kiritimati Island (doi:10.7289/V55Q4T5K), the other of 193 soundings from the NOAA Ship Ronald H. Brown (doi:10.7289/V5X63K15). Of the Kiritimati soundings, 94 % reached the tropopause and 88 % reached 40 hPa, while 89 % of the ship's soundings reached the tropopause and 87 % reached 40 hPa. The soundings captured the repeated advance and retreat of the ITCZ at Kiritimati, a variety of marine tropospheric environments encountered by the ship, and lower-stratospheric features of the 2015–2016 QBO (quasi-biennial oscillation), all providing a rich view of the local atmosphere's response to the east-central Pacific's extremely warm waters during the 2015/16 El Niño.

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The anomalous change in the QBO in 2015–2016

Cited by 175 publications

References 17 publications

Overview of experiment design and comparison of models participating in phase 1 of the SPARC Quasi-Biennial Oscillation initiative (QBOi)

Overview of experiment design and comparison of models participating in phase 1 of the SPARC Quasi-Biennial Oscillation initiative (QBOi)

On the origin of the mesospheric quasi-stationary planetary waves in the unusual Arctic winter 2015/2016

Ship- and island-based soundings from the 2016 El Niño Rapid Response (ENRR) field campaign

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