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Guoxiong Wu and Yimin Liu

regional as well as global climate. Some of the results are summarized in this study, and can be considered as a complement to the review of Yanai and Wu (2006) . Both the diagnosis and numerical experiments are used to get new insights into our understanding. The remainder of this chapter is organized as follows. In section 2 , there is an analysis of the relative importance of mechanical and thermal forcing induced by large-scale mountains. The diabatic heating characteristics of atmosphere over TP

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Robert A. Houze Jr.

Abstract

Joanne Simpson began contributing to advances in tropical convection about half a century ago. The hot tower hypothesis jointly put forth by Joanne Simpson and Herbert Riehl postulated that deep convective clouds populating the “equatorial trough zone” were responsible for transporting heat from the boundary layer to the upper troposphere. This hypothesis was the beginning of a 50-year quest to describe and understand near-equatorial deep convection. Tropical field experiments in the 1970s [Global Atmospheric Research Program Atlantic Tropical Experiment (GATE) and the Monsoon Experiment (MONEX)] in which Joanne participated documented the mesoscale structure of the convective systems, in particular the deep, stratiform, dynamically active mesoscale clouds that are connected with the hot towers. In the 1980s these new data led to better understanding of how tropical mesoscale convective systems vertically transport heat and momentum. The role of the mesoscale stratiform circulation in this transport was quantified. Tropical field work in the 1990s [especially the Coupled Ocean–Atmosphere Response Experiment (COARE), in which Joanne again participated] showed the importance of a still larger scale of convective organization, the “supercluster.” This larger scale of organization has a middle-level inflow circulation that appears to be an important transporter of momentum. The mesoscale and supercluster scale of organization in tropical convective systems are associated with the stratiform components of the cloud systems. Joint analysis of satellite and radar data from COARE show a complex, possibly chaotic relationship between cloud-top temperature and the size of a stratiform precipitation area. The Tropical Rainfall Measuring Mission (TRMM) satellite, for which Joanne served as project scientist for nearly a decade, is now providing a global census of mesoscale and supercluster-scale organization of tropical convection. The TRMM dataset should therefore provide some closure to the question of the nature of deep convection in the equatorial trough zone.

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Mark P. Baldwin, Thomas Birner, Guy Brasseur, John Burrows, Neal Butchart, Rolando Garcia, Marvin Geller, Lesley Gray, Kevin Hamilton, Nili Harnik, Michaela I. Hegglin, Ulrike Langematz, Alan Robock, Kaoru Sato, and Adam A. Scaife

changing BDC may have a significant role in the dynamical coupling between the stratosphere and troposphere with implications for surface climate and weather (e.g., Baldwin et al. 2007a ; Karpechko and Manzini 2012 ; Scaife et al. 2012 ). Therefore, it appears that the influences of the BDC and its response to climate change may not be solely confined to the stratosphere but are almost certainly omnipresent throughout Earth’s atmosphere. 3. Middle atmosphere dynamics theory The thermodynamic state

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Isaac M. Held

, https://doi.org/10.1175/1520-0469(1963)020<0607:ANOLSM>2.0.CO;2 . 10.1175/1520-0469(1963)020<0607:ANOLSM>2.0.CO;2 Charney , J. G. , and A. Eliassen , 1949 : A numerical method for predicting the perturbations of the middle latitude westerlies . Tellus , 1 , 38 – 54 , https://doi.org/10.3402/tellusa.v1i2.8500 . 10.3402/tellusa.v1i2.8500 Charney , J. G. , and P. G. Drazin , 1961 : Propagation of planetary-scale disturbances from the lower into the upper atmosphere . J. Geophys. Res

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David S. Battisti, Daniel J. Vimont, and Benjamin P. Kirtman

with the warm phase of ENSO (i.e., a +1 σ Niño-3.4 index), as seen in ERA-Interim reanalysis (1979–2013). (top) Total divergence and total wind, (middle) zonal wind and its contribution to divergence, and (bottom) meridional wind and its contribution to divergence. The maximum wind vector is ~1 m s −1 . [From Adames and Wallace (2017) .] 2) The response of the ocean to wind stress forcing The ENSO mode and the theory of ENSO are based on models and eigensolutions of the coupled atmosphere

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David Randall, Charlotte DeMott, Cristiana Stan, Marat Khairoutdinov, James Benedict, Rachel McCrary, Katherine Thayer-Calder, and Mark Branson

1. Introduction The tropics strongly absorb solar radiation at all times of year. Much of that solar energy is used to evaporate water at Earth’s surface. The water vapor thus added to the tropical atmosphere can be lofted to form beautiful convective cloud systems, which are organized on scales ranging from a few kilometers to many thousands of kilometers. The resulting weather systems include squall lines, tropical cyclones, and continent-spanning monsoons. The intense cloudy convective

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Larry K. Berg and Peter J. Lamb

), and Medium Range Forecast (MRF; triangles) parameterizations on 13 Aug 1996 near (top) Lamont, OK; (middle) Ringwood KS; and (bottom) Meeker, OK. Note that net radiation is defined as positive away from the surface. [Courtesy of Berg and Zhong (2005 ).] Other studies have focused on the representation of the linkages between the land or ocean and the atmosphere in GCMs. Sud et al. (2001) used measurements from the SGP site to evaluate the Goddard Earth Observing System (GEOS-2) GCM single

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David A. Randall, Cecilia M. Bitz, Gokhan Danabasoglu, A. Scott Denning, Peter R. Gent, Andrew Gettelman, Stephen M. Griffies, Peter Lynch, Hugh Morrison, Robert Pincus, and John Thuburn

perspective ( Bjerknes 1904 ). His stated goal was to make meteorology an exact science, a true physics of the atmosphere. He argued that it should be possible to predict changes in the weather by solving systems of partial differential equations, which is exactly what we do today. Fig . 12-1. (left) Cleveland Abbe (1838–1916). (middle) Vilhelm Bjerknes (1862–1951). (right) Lewis Fry Richardson (1881–1953). The English Quaker mathematician, Lewis Fry Richardson, went further. He wanted a worked example

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Greg M. McFarquhar and Robert M. Rauber

through instruments installed on satellite platforms ( Ackerman et al. 2019 ; Fu et al. 2019 ). Given the importance of the general circulation of the atmosphere ( Held 2019 ) and ocean ( Wunsch and Ferrari 2019 ) in determining properties and phenomena, these topics are summarized next along with chapters describing the dynamics of atmosphere–ocean variability ( Battisti et al. 2019 ) and Earth’s middle atmosphere ( Baldwin et al. 2019 ). Other important topical areas that impact and are impacted by

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Kazuyoshi Oouchi and Masaki Satoh

(middle panel)—that is mostly collocated with the negative temperature anomaly in the lower atmosphere, that is, the cold reservoir. This reinforces the key premise of the hypothesis. The relationship between the convection and the zonal–vertical flow fields (top panel) is also similar in that the updraft core tilts westward with height with respect to the active convection cell(s). To describe it another way, the low-level warm and moist air advances into the cold reservoir from the east, ascends to

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