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Michael G. Bosilovich, Franklin R. Robertson, Lawrence Takacs, Andrea Molod, and David Mocko

1. Introduction Reanalyses aim to construct a continuous and complete picture of the weather and climate by constraining evolving model forecasts with a large but heterogeneous mix of observations having different temporal availability, accuracy, and degree of correspondence to model state variables and fluxes. The resulting reanalysis products have proven useful in characterizing the climate ( Trenberth et al. 2011 ) and weather (O. Reale and M. Cordero-Fuentes 2016, unpublished manuscript

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

. Nevertheless, their precise impact on the simulated land surface states and fluxes in MERRA-2 requires further study. c. Imprint of corrected precipitation on near-surface meteorology Land surface hydrology is, for the most part, driven by the atmosphere. The atmosphere drives the land surface with precipitation, radiation, near-surface air temperature, near-surface humidity, and other forcing, and the land surface responds with fluxes of moisture and energy (e.g., runoff, evapotranspiration, sensible heat

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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

shown). The results obtained using the shorter time period are very similar to those presented below and do not alter the conclusions. Note that the streamflow evaluation is only through 2010 [ section 2b(4) ]. 3. Results In this section, we evaluate several land surface water stores and fluxes from MERRA-2 and demonstrate consistent improvements compared to MERRA. For reference, estimates from MERRA-Land and, where possible, ERA-Interim/Land are included in the comparison. a. Terrestrial water

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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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Bin Guan, Duane E. Waliser, and F. Martin Ralph

represents the total along-AR horizontal water vapor flux through a cross section perpendicular to an AR (analogous to the streamflow in a terrestrial river). The dataset used by Ralph et al. (2017b) had been collected using four types of research aircraft in a series of 37 research flights over nearly 20 years ( Ralph et al. 2004 , 2011 , 2016 ; Neiman et al. 2014 ), of which 30 flights were conducted during the CalWater program of field studies. Ralph et al. (2017b) concluded that on average an

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Young-Kwon Lim, Robin M. Kovach, Steven Pawson, and Guillaume Vernieres

surface salinity as well as the model-derived surface freshwater fluxes. This caveat in the salinity observing system is the cause of the large SSS differences seen between 2015 and 1997 as well as 2015 and 1982 (see Fig. 6 , top and middle). Fig . 1. SSS in situ observations for December (top) 1982, (middle) 1997, and (bottom) 2015. Observations are from Argo drifting buoys, XBT and CTD profilers, and TAO, PIRATA, and Research Moored Array for African–Asian–Australian Monsoon Analysis and Prediction

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Lawrence Coy, Krzysztof Wargan, Andrea M. Molod, William R. McCarty, and Steven Pawson

state density, a is the radius of Earth, ϕ is latitude, z is the log-pressure vertical coordinate, corresponds to the top saved pressure level (0.1 hPa), the overbar denotes a zonal average, and prime denotes deviations from the zonal average. The first term in Eq. (1) gives the northward Eulerian mass flux above the level z up to by integrating over the dummy vertical variable ζ . The second term, evaluated at , gives the small northward Eulerian mass flux between the top saved

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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

States. Over Houston MERRA-2 is missing HSRL-detected aerosol layers above the boundary layer that are likely due to long-range smoke transport from the northwestern United States. Recall that in MERRA-2 biomass burning emissions are deposited in the boundary layer without consideration of local buoyancy enhancement by fire heat fluxes (e.g., Freitas et al. 2007 ), a feature that could explain this deficiency in vertical structure (e.g., Colarco et al. 2004 ). During SEAC 4 RS, however, MERRA-2

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Gloria L. Manney and Michaela I. Hegglin

Screen 2015 , and references therein). However, many models predict a strengthening of upper-tropospheric temperature gradients, which would lead to a strengthening and poleward shift of the jets; lower- and upper-tropospheric jet responses may thus not be the same. Moreover, dynamical feedbacks resulting from the changing background winds (e.g., from changing waveguide conditions that affect wave activity, heat, and momentum fluxes) could play a role equal to or larger than that of changes in

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