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Lawrence Coy, Paul A. Newman, Steven Pawson, and Leslie R. Lait

) was responsible for the anonymous easterly acceleration near 40 hPa that characterized the 2015/16 disruption of the QBO and, in addition, that these EP flux vectors propagated into the tropics from the Northern Hemisphere. The upward and equatorward EP flux pattern noted by Osprey et al. (2016) is typical of Rossby wave propagation in the winter stratosphere ( Hamilton 1982 ); however, the effect of Rossby waves on the equatorial winds has previously been considered to be small based on

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Krzysztof Wargan, Gordon Labow, Stacey Frith, Steven Pawson, Nathaniel Livesey, and Gary Partyka

-2 to remove it. It leads to an increase of the difference between SBUV data and MERRA-2 total ozone from 1% to 2% between the tropics and northern high latitudes, as discussed below in section 6a . c. Aura MLS The Microwave Limb Sounder on the EOS Aura satellite ( Waters et al. 2006 ) measures profiles of atmospheric thermal radiation in a broad spectrum of microwave bands, allowing high-quality retrievals of temperature and concentrations of over a dozen chemical species in the stratosphere

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Gloria L. Manney and Michaela I. Hegglin

; Hudson 2012 ; Grise et al. 2013 ; Waugh et al. 2015 ), as well as to natural modes of variability such as ENSO and the quasi-biennial oscillation (QBO) ( Hudson 2012 ; Lin et al. 2014 , 2015 ; Olsen et al. 2016 , and references therein). Upper-tropospheric jets are often categorized conceptually as radiatively driven or eddy-driven jets. Radiatively driven jets arise via heating of the tropics, which drives the Hadley circulation and—through conservation of angular momentum—leads to strong

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Clara S. Draper, Rolf H. Reichle, and Randal D. Koster

input LH estimates used. Additionally, Jiménez et al. (2011) noted a sharp gradient in the MERRA LH around 10°S in the tropics that was not present in other LH estimates. This bias gradient was traced to MERRA’s excessive rainfall canopy interception and precipitation errors ( Reichle et al. 2011 ). Consequently, the interception reservoir parameters were revised for MERRA-Land (and MERRA-2) to eliminate this feature (the interception reservoir update was the most significant modeling change from

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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

a weighted mixture in between to prevent spatial discontinuities in climatological means. This is illustrated in Fig. 4 , which shows the annual average adjustment made to the model-generated precipitation in MERRA-2 for the period 1980–2015 using this technique. The greatest adjustments are made in the tropics, where precipitation is greatest and the corrected estimates are given most weight, while no adjustments are made poleward of 62.5° latitude in either hemisphere. Fig . 4. Mean

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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

note the caveat that this comparison is more qualitative than quantitative due to these important sampling differences. Figure 6 shows seasonal median of the vertical distribution of extinction from SAGE II and MERRA-2 at 525 nm averaged over the tropics (20°N–20°S) for the period from June to December 1991, the 6-month period following the 15 June 1991 eruption of Mt. Pinatubo in the Philippines; shading indicates the 25th–75th percentiles of all profiles for that period. Clearly, the MERRA-2

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

1. Introduction This study presents an analysis of the atmospheric and oceanic signals over the tropics associated with the strong El Niño event that occurred in 2015/16. For the ocean, the study uses the Goddard Earth Observing System (GEOS) oceanic analysis ( Vernieres et al. 2012 ) that is driven by the Modern-Era Retrospective Analysis for Research and Applications (MERRA) atmospheric reanalysis ( Rienecker et al. 2011 ). Atmospheric fields in this work are from the updated MERRA-2

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

weather and climate events. However, in reanalyses, the assimilation of observations can significantly affect the weather and climate representation of all terms of the water cycle. Dynamical quantities in reanalyses have more fidelity in the upper levels and mid-to-high latitudes but become more uncertain in the tropics and lower troposphere ( Rienecker et al. 2011 ). Trenberth et al. (2011) characterized the water cycle using a multitude of reanalyses. The variations among the reanalysis data are

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Allison B. Marquardt Collow and Mark A. Miller

1. Introduction The Amazon rain forest is an important component of the global carbon and hydrologic cycles and is a region within the tropics with potential climate change sensitivities, especially with the recent trend of deforestation. Climate change is driven by alterations to regional and global radiation budgets, and uncertainties remain in the relationships between the biosphere, radiation, clouds, and aerosols. It is therefore important to assemble a collection of observations from

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

use recent satellite observations, the MERRA-2 model incorporates improvements in the MERRA atmospheric circulation model ( Molod et al. 2015 ). A description of the MERRA-2 system and initial evaluation is presented in Bosilovich et al. (2015a , b) . The most relevant change from MERRA to MERRA-2 for the QBO is the model retuning of the gravity wave drag (GWD) parameterization. The latitude-dependent nonorographic GWD source was increased in the tropics by nearly a factor of 8, producing a

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