Atmos. Chem. Phys. Discuss., 13, 21927-21959, 2013
www.atmos-chem-phys-discuss.net/13/21927/2013/
doi:10.5194/acpd-13-21927-2013
© Author(s) 2013. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Evaluation of the warming structure in the Arctic
C. E. Chung1, H. Cha1, T. Vihma2, and P. Räisänen2
1School of Environmental Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
2Finnish Meteorological Institute, 00101 Helsinki, Finland

Abstract. There has been growing interest in the vertical structure of the recent Arctic warming. We investigated temperatures at the surface, 925, 700, 500 and 300 hPa levels in the Arctic (north of 70° N) using observations and four reanalyses: ERA-Interim, CFSR, MERRA and NCEP II. For the period 1979–2011, the layers at 500 hPa and below show a~warming trend in all seasons in all the chosen reanalyses and observations. Restricting the analysis to the 1998–2011 period, however, all the reanalyses show a~cooling trend in the Arctic-mean 500 hPa temperature in autumn, and this also applies to both observations and the reanalyses when restricting the analysis to the locations with available IGRA radiosoundings. During this period, the surface observations mainly representing land areas surrounding the Arctic Ocean reveal no summer-time trend, in contrast with the reanalyses whether restricted to the locations of the available surface observations or not.

In evaluating the reanalyses with observations, we find that the reanalyses agree better with each other at the available IGRA sounding locations than for the Arctic average, perhaps because the sounding observations were assimilated into reanalyses. Conversely, using the reanalysis data only from locations matching available surface (air) temperature observations does not improve the agreement between the reanalyses. At 925 hPa, CFSR deviates from the other three reanalyses especially in summer after 2000, and it also deviates more from the IGRA radiosoundings than the other reanalyses do. The CFSR error in summer T925 is due mainly to underestimations in the Canadian-Atlantic sector between 120° W and 0°. The other reanalyses also have negative biases in this longitude band.


Citation: Chung, C. E., Cha, H., Vihma, T., and Räisänen, P.: Evaluation of the warming structure in the Arctic, Atmos. Chem. Phys. Discuss., 13, 21927-21959, doi:10.5194/acpd-13-21927-2013, 2013.
 
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