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Momme C. Hell, Tapio Schneider, and Camille Li

down to the troposphere to create a negative North Atlantic Oscillation (NAO) response ( Baldwin and Dunkerton 2001 ; Polvani and Waugh 2004 ), along with its associated surface climate effects ( Kolstad et al. 2010 ; Scaife et al. 2005 ; Ambaum and Hoskins 2002 ; Thompson and Wallace 1998 ). A number of studies have investigated the existence of this stratospheric pathway linking Arctic sea ice loss to a midlatitude circulation response, but the results are not clear-cut. There is evidence

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B. J. H. Van de Wiel, A. F. Moene, G. J. Steeneveld, P. Baas, F. C. Bosveld, and A. A. M. Holtslag

. , and W. Blumen , 1997 : A dynamic trio: Inertial oscillation, deformation frontogenesis, and the Ekman–Taylor boundary layer. J. Atmos. Sci. , 54 , 1490 – 1502 . ReVelle , D. O. , and E. D. Nilsson , 2008 : Summertime low-level jets, over the high-latitude Arctic Ocean. J. Appl. Meteor. Climatol. , 47 , 1770 – 1784 . Shapiro , A. , and E. Fedorovich , 2009 : Nocturnal low-level jet over a shallow slope. Acta Geophys. , 57 , 950 – 980 . Shapiro , A. , and E

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Darryn W. Waugh and William J. Randel

of a biennel oscillation (see also Baldwin and Dunkerton 1998 ). Also, there appears to be a slight “trend” in the lifetime of both vortices, with the vortices lasting longer in more recent years. We now consider in more detail the interannual variability of each vortex. a. Arctic vortex The variation of Δ φ C (solid curve) and δ (dashed) at 850 K for the individual Arctic winters (December–February) from 1990/91 to 1997/98 is shown in Fig. 13 . As expected from Fig. 11 , there is large

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I. P. Semiletov

CO 2 fluxes shows that net transfer between 53°S and Antarctic might be reversed from sink (in 1992) to source (in 1993), which may indicate a change in the balance between photosynthesis and respiration in this area ( Ciais et al. 1995b ) or a small oscillation in the present-day large-scale thermohaline circulation pattern of the ocean ( Broecker 1997 ). Comparison of the autumn ΔpCO 2 distribution for Arctic ( Figs. 2a,b ) and Antarctic ( Fig. 4 ) shows that in both regions the water cooling

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Timothy W. Cronin, Harrison Li, and Eli Tziperman

under global warming . Climate Dyn. , 40 , 2415 – 2431 , doi: 10.1007/s00382-011-1279-7 . 10.1007/s00382-011-1279-7 Chylek , P. , C. K. Folland , G. Lesins , M. K. Dubey , and M. Wang , 2009 : Arctic air temperature change amplification and the Atlantic multidecadal oscillation. Geophys . Res. Lett. , 36 , L14801 , doi: 10.1029/2009GL038777 . 10.1029/2009GL038777 Cronin , T. W. , and K. A. Emanuel , 2013 : The climate time scale in the approach to radiative

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Ryosuke Shibuya, Kaoru Sato, and Mikio Nakanishi

diurnal variations of the ABL by using wind profiler network data in a systematic way like Baas et al. (2012) . Moreover, such oscillations in the ABL can be a strong source of inertia–gravity waves, which are frequently observed in the free atmosphere. Further studies from this point of view are also necessary. Acknowledgments The authors thank Professor Hiroaki Miura for instructive advice. This study is partly supported by the GRENE Arctic Climate Change Research Project. REFERENCES Baas , P

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Timothy J. Dunkerton

trace constituent behavior. Coupling of the polar troposphere and lower stratosphere was observed in northern winter as a leading empirical orthogonal function (EOF) or SVD mode ( Baldwin et al. 1994 ) also known as the Arctic Oscillation ( Thompson and Wallace 1998 , 2000 ). Interaction between the annual cycle and the QBO was found in the stratosphere by examining the frequency spectrum of the leading principal component of angular momentum ( Baldwin and Tung 1994 ). Randel et al. (1998) used

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Jiansong Zhou and Ka-Kit Tung

for this purpose. Typical regressors (also called explanatory or predictor variables) are El Niño–Southern Oscillation (ENSO), volcano aerosol optical depth, total solar irradiance (TSI) (11-yr solar cycle plus the secular solar forcing trend), and the anthropogenic warming trend. These are specified as a function of time. MLR is used to fit the observed temperature time series using these regressors, with the residual assumed to be a white or red noise. When the residual is tested to be a noise

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Gilles Bellon and Adam Sobel

disturbances, and understanding the 30–60-day mode is therefore crucial to the seasonal forecast of the onset. About half of these northward-propagating disturbances are associated with the equatorial eastward-propagating Madden–Julian oscillation (MJO; Wang and Rui 1990 ). Consequently, studies have presented the northward propagation of the tropical convergence zone as a Rossby wave emanating from an MJO Kelvin–Rossby packet ( Wang and Xie 1997 ; Lawrence and Webster 2002 ). These studies suggest that

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M. M. Hurwitz, P. A. Newman, L. D. Oman, and A. M. Molod

1. Introduction El Niño–Southern Oscillation (ENSO) has a stratospheric signature in both the tropics and in the Arctic. In the tropics, the lower-stratospheric temperature response to ENSO is opposite in sign to that in the troposphere; that is, a cooling associated with ENSO warm phase (El Niño) events ( Calvo Fernandez et al. 2004 ; García-Herrera et al. 2006 ; Free and Seidel 2009 ). This upper-tropospheric warming and lower-stratospheric cooling reflects a strengthened tropical upwelling

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