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

must first be addressed. Several studies have investigated the performance of reanalyses over the Arctic for a variety of fields including atmospheric moisture budgets ( Bromwich et al. 2000 , 2002 ), upper-level winds ( Francis 2002 ), precipitation ( Serreze and Hurst 2000 ), cloud fraction (CF) and radiative fluxes ( Walsh et al. 2009 ), and general tropospheric assessments ( Bromwich and Wang 2005 ; Bromwich et al. 2007 ). These studies, however, were based on the earlier generations of

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Kyle F. Itterly and Patrick C. Taylor

monsoon season using both observations and reanalyses and found large disparities in cloud amounts between the observed and modeled values. Few studies, however, have evaluated the tropical diurnal cycle of TOA fluxes in reanalyses. This study fills a gap in the evaluation of reanalysis models: namely, documenting the fidelity of the TOA flux diurnal cycle in the tropics. The purpose of this study is to evaluate and document the diurnal cycle representation of the TOA radiative flux in two reanalysis

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Aaron D. Kennedy, Xiquan Dong, Baike Xi, Shaocheng Xie, Yunyan Zhang, and Junye Chen

, including ground-based observed cloud, precipitation, and radiative fluxes, provide a unique dataset to evaluate these parameters from the reanalyses. The ARM SGP site is representative of a continental climate in the midlatitudes, and it has been used successfully in the past to evaluate a variety of model simulations, including the NCEP Eta Model ( Hinkelman et al. 1999 ), ECMWF ( Xie et al. 2004 ), and the NCEP Global Forecast System (GFS) ( Yang et al. 2006 ). This 3-yr comparison will assist in

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

study focuses on global land areas with additional emphasis on northern high-latitude regions (>45°N), where terrestrial carbon, water, and energy fluxes provide potentially important climate feedbacks and modeling efforts rely heavily on global reanalysis data. 2. Data The datasets and in situ observations used for evaluation and validation of the MERRA land parameters in this study are summarized in Table 1 . We evaluated GEOS-4 and MERRA surface meteorological data against AMSR-E [University of

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Derek J. Posselt, Andrew R. Jongeward, Chuan-Yuan Hsu, and Gerald L. Potter

the western to central Pacific. Almost as remarkable as the strength of the event was the rapidity of its transition to a La Niña state in the middle of 1998. Cloud properties and radiative fluxes during the 1998 El Niño–La Niña transition were observed by the Tropical Rainfall Measuring Mission (TRMM) satellite and the instruments on board have been used to identify sets of contiguous cloud features or “objects” in the data ( Xu et al. 2005 , 2007 , 2008 ). A subset of these objects is

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Franklin R. Robertson and Jason B. Roberts

on the Modern-Era Retrospective analysis for Research and Applications (MERRA; Rienecker et al. 2011) . More specifically, we ask what insights can MERRA, along with other observations, provide regarding the role of ISV in near-global radiative–convective adjustment and energy balance? Our focus therefore is not just on the state variables, but also on the energy fluxes. As noted by Kalnay et al. (1996) precipitation, turbulent fluxes, and cloud radiative effects derived from reanalyses

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Michael A. Brunke, Zhuo Wang, Xubin Zeng, Michael Bosilovich, and Chung-Lin Shie

). Another shortcoming of the satellite-derived products is that they do not generally provide radiative fluxes, which are also needed to study the surface energy budget or to force an OGCM, whereas they are generally not provided in the satellite-derived products [HOAPS does provide the net longwave (LW) flux but not the net shortwave (SW) flux]. Table 4 presents the mean difference in surface downward LW and SW radiative fluxes between the reanalysis values and ship observations from all of the

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J. Brent Roberts, Franklin R. Robertson, Carol A. Clayson, and Michael G. Bosilovich

and radiative fluxes. However, by construction, all models have tunable parameters and physics biases and the observations themselves have significant uncertainties. Thus, understanding and characterizing the behavior of these assimilated products is a key part of validating the overall performance of MERRA and other reanalyses. Here, we use direct in situ buoy and ship observations along with gridded, observationally based datasets to provide an initial characterization of the NASA MERRA product

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

cycle that is much too large over land during the warm seasons ( Janowiak et al. 1998 ). Similarly, Berg et al. (2003) found that the NCEP–NCAR reanalysis and ERA-40 have substantial biases in 2-m air and dewpoint temperatures, surface radiative fluxes, and precipitation over land in North America as compared with various gridded datasets. Aside from the atmospheric fields used to force land surface models, evapotranspiration during the warm season over the U.S. Great Plains region has also been

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

integrals of heat and water budget components (tavgM_2d_int_Nx and tavgM_2d_int_Nx) and individual radiative flux components (tavgM_2d_rad_Nx) for the period 1979–2009. These quantities at their native resolution (0.50° latitude × 0.67° longitude) were regridded via box averaging to a 2.5° latitude × 2.5° longitude grid to facilitate computing covariance statistics. More detailed documentation on the quantities in these datasets can be found in the MERRA File Specification Document ( Suarez et al. 2010

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