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Nili Harnik, Judith Perlwitz, and Tiffany A. Shaw

2 and U zz . We see that N 2 shows a significant negative trend, while U zz shows no significant trend (if anything, it is a small negative trend). This suggests that although the interannual variability in m 2 stems from changes in N 2 and U zz , only the former contributes to the observed trend. These results indicate that the observed decadal changes in m 2 can be explained by observed significant trends in the mean flow zonal wind and temperature structure. Fig . 3. Yearly

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Franklin R. Robertson, Michael G. Bosilovich, Junye Chen, and Timothy L. Miller

1. Introduction Steady progress in data assimilation efforts has produced a legacy of important contributions regarding atmospheric dynamics ( Dole 1989 ; Simmonds and Keay 2000 ; Thompson and Wallace 1998 , 2000 ; Thompson et al. 2000 ; Hoskins and Hodges 2005 ), tropical water and energy fluxes, and climate variability on interannual time scales ( Trenberth et al. 2000 , 2001 , 2008 ; Bove et al. 1998 ; Wang 2002 ). Yet, as a tool for capturing decadal-scale variability and detection

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Michael G. Bosilovich, Franklin R. Robertson, and Junye Chen

indicators of trends ( Kalnay and Cai 2003 ), there are numerous examples of artifacts dominating real physical trends from reanalysis data. For example, ERA-40 precipitation has strong decadal interannual variability of tropical precipitation that does not appear in observations ( Uppala et al. 2005 ; Andersson et al. 2005 ). Likewise, JRA-25 precipitation exhibits a stepwise shift when SSM/I retrieved total column water becomes available for assimilation ( Onogi et al. 2005 ). In this section, we

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Tiffany A. Shaw, Judith Perlwitz, Nili Harnik, Paul A. Newman, and Steven Pawson

. S. Lindzen , 2001 : The effect of reflecting surfaces on the vertical structure and variability of stratospheric planetary waves . J. Atmos. Sci. , 58 , 2872 – 2894 . Harnik , N. , J. Perlwitz , and T. A. Shaw , 2011 : Observed decadal changes in downward wave coupling between the stratosphere and troposphere in the Southern Hemisphere . J. Climate , in press . Hu , Y. , and Q. Fu , 2009 : Stratospheric warming in Southern Hemisphere high latitudes since 1979 . Atmos

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David H. Bromwich, Julien P. Nicolas, and Andrew J. Monaghan

1. Introduction Over the last decade, there has been increasing evidence of a positive contribution of the Antarctic Ice Sheet to global sea level rise ( Allison et al. 2009 ). The corresponding ice mass loss is mainly driven by enhanced ice discharge into the ocean from West Antarctica and the Antarctic Peninsula ( Rignot et al. 2008 ; Pritchard et al. 2009 ); see geographic names in Fig. 1 . There is, however, considerable uncertainty as to how the ice sheet’s surface mass balance (SMB) has

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Mark Decker, Michael A. Brunke, Zhuo Wang, Koichi Sakaguchi, Xubin Zeng, and Michael G. Bosilovich

every single station in terms of the 6-hourly air temperature. The ratio of standard deviations also shows that the products match the observed 6-hourly variation in temperature very well, as nearly all of the stations fall within a range of 0.9–1.1, meaning that there is a less than 10% error for the variation of temperature. However, CFSR tends to underestimate the variability in the 6-hourly temperature, as seven stations (Aud, Fpe, KS2, LPH, Los, SP2, and Wsc) have a ratio of standard deviations

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Franklin R. Robertson and Jason B. Roberts

. Balsamo , 2008 : Advances in simulating atmospheric variability with the ECMWF model: From synoptic to decadal time-scales . Quart. J. Roy. Meteor. Soc. , 134 , 1337 – 1351 , doi:10.1002/qj.289 . Benedict , J. J. , and D. A. Randall , 2007 : Observed characteristics of the MJO relative to maximum rainfall . J. Atmos. Sci. , 64 , 2332 – 2354 . Blade , I. , and D. L. Hartmann , 1993 : Tropical intraseasonal oscillations in a simple nonlinear model . J. Atmos. Sci. , 50 , 2922

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Michele M. Rienecker, Max J. Suarez, Ronald Gelaro, Ricardo Todling, Julio Bacmeister, Emily Liu, Michael G. Bosilovich, Siegfried D. Schubert, Lawrence Takacs, Gi-Kong Kim, Stephen Bloom, Junye Chen, Douglas Collins, Austin Conaty, Arlindo da Silva, Wei Gu, Joanna Joiner, Randal D. Koster, Robert Lucchesi, Andrea Molod, Tommy Owens, Steven Pawson, Philip Pegion, Christopher R. Redder, Rolf Reichle, Franklin R. Robertson, Albert G. Ruddick, Meta Sienkiewicz, and Jack Woollen

meteorological forcing fields and surface fluxes over land from MERRA and other reanalyses with satellite estimates and in situ observations from flux towers. Roberts et al. (2011, manuscript submitted to J. Climate ) and Brunke et al. (2011) analyze surface turbulent fluxes over the ocean from MERRA and other data products. Harnik et al. (2011) use MERRA to analyze decadal changes in downward wave coupling between the stratosphere and troposphere. By identifying both the strengths and weaknesses of the

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Yonghong Yi, John S. Kimball, Lucas A. Jones, Rolf H. Reichle, and Kyle C. McDonald

land surface hydrological processes through explicit modeling of subgrid-scale soil moisture variability and its effect on runoff and evaporation ( Koster et al. 2000 ). The basic computational unit of the model is the hydrological catchment (or watershed), with boundaries defined by topography. Within each element, the vertical profile of soil moisture is given by the equilibrium soil moisture profile and deviations from the equilibrium profile in a 0–2-cm surface layer and 0–100-cm “root zone

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Behnjamin J. Zib, Xiquan Dong, Baike Xi, and Aaron Kennedy

1. Introduction Over the past few decades, atmospheric reanalysis datasets have provided a long-term, gridded representation of the state of the atmosphere while offering a resource for investigating climate processes and predictability. Reanalyses utilize observations through state-of-the-art data assimilation systems. Combined with underlying models, they provide a continuous data record that consists of various atmospheric variables describing (diagnosing) past weather conditions. Reanalyses

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