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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
doi:10.5194/acp-2017-289
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
07 Apr 2017
Review status
This discussion paper is under review for the journal Atmospheric Chemistry and Physics (ACP).
Climatology and Interannual Variability of Dynamic Variables in Multiple Reanalyses Evaluated by the SPARC Reanalysis Intercomparison Project (S-RIP)
Craig S. Long1, Masatomo Fujiwara2, Sean Davis3,4, Daniel M. Mitchell5, and Corwin J. Wright6 1Climate Prediction Center, National Centers for Environmental Prediction, National Oceanic and Atmospheric, Administration, College Park, MD 20740, USA
2Faculty of Environmental Earth Science, Hokkaido University, Sapporo, 060-0810, Japan
3Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, USA
4Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder, Boulder, CO 80309, USA
5School of Geographical Sciences, University of Bristol, Bristol, UK
6Centre for Space, Atmosphere and Ocean Science, University of Bath, Claverton Down, Bath, UK
Abstract. 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 both observed by conventional systems, cloud tracked, and derived from height fields which in turn are 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 between the reanalyses themselves, but comparisons against independent observations such as HIRDLS temperatures are also presented. This evaluation uses monthly mean and 2.5 degree zonal mean data sets and spans the satellite era from 1979–2014. There is very good agreement in temperature seasonally and latitudinally between 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 between 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 (1979–1998) and less variance afterward in the ATOVS period (1999–2014). 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, ERA-Interim, JRA-55) are similarly observed when compared with Aura/HIRDLS and Aura/MLS observations. There is good agreement between NOAA's 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.

Citation: Long, C. S., Fujiwara, M., Davis, S., Mitchell, D. M., and Wright, C. J.: Climatology and Interannual Variability of Dynamic Variables in Multiple Reanalyses Evaluated by the SPARC Reanalysis Intercomparison Project (S-RIP), Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-289, in review, 2017.
Craig S. Long et al.
Craig S. Long et al.
Craig S. Long et al.

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Short summary
As part of the SPARC-Reanalysis Intercomparison Project we evaluate the temperature and wind structure of all the recent and past reanalyses. 2.5 degree monthly zonal mean data sets are used from 1979 2014. There is a distinct change in the temperature structure in the stratosphere in 1998. Zonal winds are in greater agreement than temperatures. All reanalyses have issues analysing the tropical stratospheric winds. Caution is advised for using reanalysis temperatures for trend detection.
As part of the SPARC-Reanalysis Intercomparison Project we evaluate the temperature and wind...
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