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Allison B. Marquardt Collow and Mark A. Miller

with a resolution of 15 min demonstrated the impact of clouds on the downwelling shortwave (SW) radiation, and variability in the SW RFD resulting from changing cloud cover was easily detected through analyzing the SW radiation budget in combination with cloud radar data. Slingo et al. (2009) later expanded this study using the same dataset to provide a seasonal view over the West African Sahel and demonstrated that water vapor in the wet season prevented a portion of longwave (LW) radiation at

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Gloria L. Manney and Michaela I. Hegglin

westerly winds in the subtropical upper troposphere (e.g., Held and Hou 1980 ). Eddy-driven jets are maintained by disturbances in the atmospheric zonal mean flow ( Held and Hoskins 1985 ; Lorenz and Hartmann 2003 ; Robinson 2006 ; Baldwin et al. 2007 ; Garfinkel et al. 2013 , and references therein). However, observations show a complex seasonally and regionally varying picture in which distinct radiatively driven or eddy-driven jets cannot be identified (e.g., Manney et al. 2014 ), consistent

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Franklin R. Robertson, Michael G. Bosilovich, and Jason B. Roberts

; Ting et al. 2011 ] also modulate moisture transport. Anthropogenic radiative forcing changes and the consequent hydrologic cycle effects are expected to produce regional variations, encapsulated in the “wet get wetter and dry get drier” paradigm ( Chou and Neelin 2004 ) wherein hydrologic extremes are expected to increase. As yet, evidence for this behavior in observational datasets is weak at best ( Greve et al. 2014 ). There is also substantial uncertainty as to trends in soil moisture dryness

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Rolf H. Reichle, Clara S. Draper, Q. Liu, Manuela Girotto, Sarith P. P. Mahanama, Randal D. Koster, and Gabrielle J. M. De Lannoy

paper, we use the term “anomalies” when we refer to time series for which the mean seasonal cycle has been subtracted. The correlation coefficient of the anomaly time series is referred to as the “anomaly R ” value; note that the anomaly R metric typically implies a more stringent assessment in that this metric does not measure (sometimes uninformative) skill from large and reliable seasonal variations. For a given evaluation, common masks and minimum data requirements were applied to all

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Ronald Gelaro, Will McCarty, Max J. Suárez, Ricardo Todling, Andrea Molod, Lawrence Takacs, Cynthia A. Randles, Anton Darmenov, Michael G. Bosilovich, Rolf Reichle, Krzysztof Wargan, Lawrence Coy, Richard Cullather, Clara Draper, Santha Akella, Virginie Buchard, Austin Conaty, Arlindo M. da Silva, Wei Gu, Gi-Kong Kim, Randal Koster, Robert Lucchesi, Dagmar Merkova, Jon Eric Nielsen, Gary Partyka, Steven Pawson, William Putman, Michele Rienecker, Siegfried D. Schubert, Meta Sienkiewicz, and Bin Zhao

also includes a Tokioka-type trigger on deep convection as part of the RAS convective parameterization scheme ( Moorthi and Suárez 1992 ), which governs the lower limit on the allowable entrainment plumes ( Bacmeister and Stephens 2011 ). A new glaciated land representation and seasonally varying sea ice albedo have been implemented, leading to improved air temperatures and reduced biases in the net energy flux over these surfaces ( Cullather et al. 2014 ). b. Analysis algorithm The control

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Rolf H. Reichle, Q. Liu, Randal D. Koster, Clara S. Draper, Sarith P. P. Mahanama, and Gary S. Partyka

gauge inputs. Nevertheless, GPCPv2.2, CMAP, and, to a lesser extent, CPCU data share a substantial portion of their raw gauge and/or satellite radiance inputs. As our results will illustrate ( section 3 ), the GPCPv2.2 data are a useful but by no means independent reference for the evaluation of the corrected reanalysis precipitation. Prior to their use in the MERRA-2 precipitation correction algorithm, the CMAP data are rescaled to match the (seasonally varying) climatology of the GPCPv2.1 pentad

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V. Buchard, C. A. Randles, A. M. da Silva, A. Darmenov, P. R. Colarco, R. Govindaraju, R. Ferrare, J. Hair, A. J. Beyersdorf, L. D. Ziemba, and H. Yu

radiative effects . Atmos. Chem. Phys. , 16 , 2507 – 2523 , doi: 10.5194/acp-16-2507-2016 . 10.5194/acp-16-2507-2016 Hand , J. , and Coauthors , 2011 : Spatial and seasonal patterns and temporal variability of haze and its constituents in the United States: Report V June 2011. Cooperative Institute for Research in the Atmosphere, Colorado State University, 507 pp. [Available online at

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C. A. Randles, A. M. da Silva, V. Buchard, P. R. Colarco, A. Darmenov, R. Govindaraju, A. Smirnov, B. Holben, R. Ferrare, J. Hair, Y. Shinozuka, and C. J. Flynn

a seasonal variation on the data volume for satellite sensors during the EOS period. 3) Data counts from MISR and AERONET are more clearly seen in the supplementary figures. For the pre-EOS period and until 2002, we assimilate bias-corrected AOD derived from the 25-yr record of AVHRR radiances ( Heidinger et al. 2014 ). We discontinue AVHRR assimilation after 2002 when MODIS Aqua becomes available; both instruments have afternoon equator crossing times. Note that AVHRR only provided AOD

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Allison B. Marquardt Collow, Michael G. Bosilovich, and Randal D. Koster

global precipitation and surface evaporation ( Reichle and Liu 2014 ; Takacs et al. 2016 ). MERRA-2 also features numerous developments in the underlying model ( Molod et al. 2015 ), such as in the surface layer and boundary layer parameterizations and in the cumulus convection scheme. The data assimilation has been updated to the latest Gridpoint Statistical Interpolation analysis scheme version and includes global dry mass constraints that help minimize spurious temporal variability effects

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Laura M. Hinkelman

minimizes the seasonal effects of vegetation in the Southern Hemisphere.) However, in MERRA, the late summer dip is minimized, and a springtime depression is exaggerated, resulting in two minima of similar magnitude. The steeper decrease in springtime is likely due to the use of a lower albedo for sea ice in the Northern Hemisphere in the earlier version of MERRA ( Gelaro et al. 2017 ), while the reduced summer dip corresponds to lower cloud radiative effect, as discussed below. The annual cycle of the

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