Dynamical Consistency of Reanalysis Datasets in the Extratropical Stratosphere

Martineau, Patrick; Son, Seok‐Woo; Taguchi, Masakazu

doi:10.1175/jcli-d-15-0469.1

Cited by 28 publications

(32 citation statements)

References 31 publications

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“…These changes near the tropopause may increase the persistence of the negative NAM phase in the troposphere (Fig. 3b), potentially providing a source of predictive skill for up to 60 days after the occurrence of the SSW (Maycock and Hitchcock, 2015). Following the SSW, the stratospheric ozone over the polar cap is greatly enhanced (Fig.…”

Section: Composite Analysismentioning

confidence: 99%

A sudden stratospheric warming compendium

Butler

Sjoberg

Seidel

et al. 2017

Earth Syst. Sci. Data

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Abstract. Major, sudden midwinter stratospheric warmings (SSWs) are large and rapid temperature increases in the winter polar stratosphere are associated with a complete reversal of the climatological westerly winds (i.e., the polar vortex). These extreme events can have substantial impacts on winter surface climate, including increased frequency of cold air outbreaks over North America and Eurasia and anomalous warming over Greenland and eastern Canada. Here we present a SSW Compendium (SSWC), a new database that documents the evolution of the stratosphere, troposphere, and surface conditions 60 days prior to and after SSWs for the period 1958-2014. The SSWC comprises data from six different reanalysis products: MERRA2

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Section: Composite Analysismentioning

confidence: 99%

A sudden stratospheric warming compendium

Butler

Sjoberg

Seidel

et al. 2017

Earth Syst. Sci. Data

328

316

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“…Mitchell et al (2015) performed a multiple linear regression analysis on the same nine reanalyses to test the robustness of their variability. Martineau et al (2016) intercompare eight reanalyses (ERA-40, ERA-I, R1, R2, CFSR, JRA-25, JRA-55, and MERRA) for dynamical consistency of wintertime stratospheric polar vortex variability. Kawatani et al (2016) compare the representation of the monthly mean zonal wind in the equatorial stratosphere with a focus on the quasi-biennial oscillation (QBO; Baldwin et al, 2001) among nine reanalyses (R1, R2, CFSR, ERA-40, ERA-I, JRA-25, JRA-55, MERRA, and MERRA-2).…”

Section: Introductionmentioning

confidence: 99%

Climatology and interannual variability of dynamic variables in multiple reanalyses evaluated by the SPARC Reanalysis Intercomparison Project (S-RIP)

et al. 2017

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Abstract. Two of the most basic parameters generated from a reanalysis are temperature and winds. Temperatures in the reanalyses are derived from conventional (surface and balloon), aircraft, and satellite observations. Winds are observed by conventional systems, cloud tracked, and derived from height fields, which are in turn derived from the vertical temperature structure. In this paper we evaluate as part of the SPARC Reanalysis Intercomparison Project (S-RIP) the temperature and wind structure of all the recent and past reanalyses. This evaluation is mainly among the reanalyses themselves, but comparisons against independent observations, such as HIRDLS and COSMIC temperatures, are also presented. This evaluation uses monthly mean and 2.5 • zonal mean data sets and spans the satellite era from 1979-2014. There is very good agreement in temperature seasonally and latitudinally among the more recent reanalyses (CFSR, MERRA, ERA-Interim, JRA-55, and MERRA-2) between the surface and 10 hPa. At lower pressures there is increased variance among these reanalyses that changes with season and latitude. This variance also changes during the time span of these reanalyses with greater variance during the TOVS period (1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998) and less variance afterward in the ATOVS period (1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014). There is a distinct change in the temperature structure in the middle and upper stratosphere during this transition from TOVS to ATOVS systems. Zonal winds are in greater agreement than temperatures and this agreement extends to lower pressures than the temperatures. Older reanalyses (NCEP/NCAR, NCEP/DOE, ERA-40, JRA-25) have larger temperature and zonal wind disagreement from the more recent reanalyses. All reanalyses to date have issues analysing the quasi-biennial oscillation (QBO) winds. Comparisons with Singapore QBO winds show disagreement in the amplitude of the westerly and easterly anomalies. The disagreement with Singapore winds improves with the transition from TOVS to ATOVS observations. Temperature bias characteristics determined via comparisons with a reanalysis ensemble mean (MERRA, ERAInterim, JRA-55) are similarly observed when compared with Aura HIRDLS and Aura MLS observations. There is good agreement among the NOAA TLS, SSU1, and SSU2 Climate Data Records and layer mean temperatures from the more recent reanalyses. Caution is advised for using reanalysis temperatures for trend detection and anomalies from a long climatology period as the quality and character of reanalyses may have changed over time.

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“…However, an accurate, process-based quantification remains elusive as a result of a large spread in the solar UV and ozone measurements (Ermolli et al 2013;Hood et al 2015;Ball et al 2016), uncertainties among reanalysis datasets (Dee et al 2011;Lu et al 2015;Mitchell et al 2015a;Martineau et al 2016), and model biases (Mitchell et al 2015b;Dhomse et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Stratospheric Response to the 11-Yr Solar Cycle: Breaking Planetary Waves, Internal Reflection, and Resonance

Gray

White

et al. 2017

Journal of Climate

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Breaking planetary waves (BPWs) affect stratospheric dynamics by reshaping the waveguides, causing internal wave reflection, and preconditioning sudden stratospheric warmings. This study examines observed changes in BPWs during the northern winter resulting from enhanced solar forcing and the consequent effect on the seasonal development of the polar vortex. During the period 1979-2014, solar-induced changes in BPWs were first observed in the uppermost stratosphere. High solar forcing was marked by sharpening of the potential vorticity (PV) gradient at 308-458N, enhanced wave absorption at high latitudes, and a reduced PV gradient between these regions. These anomalies instigated an equatorward shift of the upper-stratospheric waveguide and enhanced downward wave reflection at high latitudes. The equatorward refraction of reflected waves from the polar upper stratosphere then led to enhanced wave absorption at 358-458N and 7-20 hPa, indicative of a widening of the midstratospheric surf zone. The stratospheric waveguide was thus constricted at about 458-608N and 5-10 hPa in early boreal winter; reduced upward wave propagation through this region resulted in a stronger upper-stratospheric westerly jet. From January, the regions with enhanced BPWs acted as ''barriers'' for subsequent upward and equatorward wave propagation. As the waves were trapped within the stratosphere, anomalies of zonal wavenumbers 2 and 3 were reflected poleward from the stratospheric surf zone. Resonant excitation of some of these reflected waves resulted in rapid growth of wave disturbances and a more disturbed polar vortex in late winter. These results provide a process-oriented explanation for the observed solar cycle signal. They also highlight the importance of nonlinearity in the processes that drive the stratospheric response to external forcing.

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Dynamical Consistency of Reanalysis Datasets in the Extratropical Stratosphere

Cited by 28 publications

References 31 publications

A sudden stratospheric warming compendium

A sudden stratospheric warming compendium

Climatology and interannual variability of dynamic variables in multiple reanalyses evaluated by the SPARC Reanalysis Intercomparison Project (S-RIP)

Stratospheric Response to the 11-Yr Solar Cycle: Breaking Planetary Waves, Internal Reflection, and Resonance

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