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Mark Yin-Mao Wang, George Tai-Jen Chen, Chung-Chieh Wang, and Ying-Hwa Kuo

processes, the effect of diabatic latent heating upstream (west) of the trough has also been investigated for events in Europe and Africa (e.g., Massacand et al. 2001 ; Knippertz and Martin 2007 ). It is found that the convection can amplify the upstream ridge and produce stronger northerly flow and PV advection, cause the trough to narrow and extend farther southward, and eventually aid to the subsequent cutoff (also Moore et al. 2008 ; Meier and Knippertz 2009 ). For Palmer-type CCLs, in a study

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Eric Tromeur and William B. Rossow

relative frequency of occurrence (RFO) for each cloud regimes (weather state). Composite vertical and horizontal velocities, as well as specific humidity, are also analyzed in order to explore the interaction between tropical convection and the large-scale circulation in the MJO. In particular, we want to evaluate the quality of reanalysis data and to make sure that weak MJOs observed in our analysis are not an artifact. The analysis is then extended to the complete atmospheric diabatic heating by

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Andrew B. Penny, Patrick A. Harr, and James D. Doyle

small number of tropical disturbances actually develop into tropical cyclones (e.g., Kerns and Chen 2013 ). In the idealized simulations by Nicholls and Montgomery (2013) , two pathways to genesis were observed. One pathway is similar to that described by Hendricks et al. (2004) and Montgomery et al. (2006) in that positive low-level vorticity is concentrated in vortical hot towers (VHTs) and the net diabatic heating from numerous VHTs helps drive low-level convergence and leads to the

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Dimitry Smirnov, Matthew Newman, Michael A. Alexander, Young-Oh Kwon, and Claude Frankignoul

-level diabatic heating anomaly, is a slightly downstream surface cyclonic anomaly. Because of time-mean meridional temperature gradients in the midlatitudes, this circulation balances the SST-induced warming with cold air advection. This results in subsidence (excluding boundary layer Ekman pumping) over the SST anomaly, as column shrinking is required to conserve vorticity and balance the equatorward flow, yielding a baroclinic structure with a downstream upper-level high. This basic picture does not tend

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Wenju Cai, Peter van Rensch, Tim Cowan, and Harry H. Hendon

). During El Niño the pressure in the east (west) pole is anomalously low (high) in conjunction with warm (cool) SST anomalies and enhanced (reduced) rainfall in the central Pacific (the Maritime Continent); the opposite occurs during La Niña. The development of the SO, at least its tropical component, is well understood as the thermally direct response of the tropical atmosphere to the diabatic heating associated with the anomalous zonal dipole in rainfall (e.g., Gill 1980 ): lower

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Chidong Zhang and Jian Ling

–circulation interaction [see reviews by Wang (2005) , Zhang (2005) , and Raymond and Fuchs (2009) ]. While MJO wind can be related to convective and synoptic momentum transport ( Tung and Yanai 2002 ; Moncrieff 2004 ; Biello and Majda 2005 ), convective diabatic heating is the main energy source for the MJO ( Yanai et al. 2000 ). Potential vorticity (PV) is a quantity that relates the nondivergent circulation directly to diabatic heating. Its characteristics associated with the MJO, however, have never been

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Boqi Liu, Guoxiong Wu, Jiangyu Mao, and Jinhai He

, together with diabatic heating, is thought to be responsible for the vortex formation ( Krishnamurti et al. 1981 ; Krishnamurti 1981 , 1985 ; Krishnamurti and Ramanathan 1982 ; Mao and Wu 2011 ). Mak and Kao (1982) showed that vertical wind shear and baroclinic instability are also important for the vortex development. In addition to these internal dynamics, Joseph (1990) proposed that the vortex is also influenced by the local sea surface temperature (SST) because, if the SST is above 28°C and

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Anmin Duan and Guoxiong Wu

heating and radiative cooling are investigated to give an overall picture of the change in the atmospheric heating status over the TP. The relationship between the diabatic heating over the TP and the global climate change in decadal time scale is assessed in section 6 , followed by conclusions and discussions in section 7 . 2. Data and methodology a. Data The data used in this study include the following sources: The regular surface meteorological observations with an initial quality control for

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Kevin E. Trenberth and John T. Fasullo

of heating and friction. The vertically integrated P e is given by after integrating by parts and using the hydrostatic approximation and equation of state, where T is temperature, R is the gas constant, and z s is the surface geopotential height. Hence , where the sensible heat , c p is the specific heat at constant pressure, and Φ s = gz s is the surface geopotential. The thermodynamic equation can be written in advective form as where Q 1 the diabatic heating per unit mass

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Christian M. Grams and Heather M. Archambault

), where vertically deep ascent occurs in the lower half of the troposphere that becomes more slantwise along the (moist) isentropes at upper levels. This ascent is supported by upper-level forcing (cf. Fig. 7b ), which is characteristic of PRE convection. Latent heat release (not shown) results in diabatically produced positive PV at lower levels just ahead of the baroclinic zone and marks the center of the PRE (2200 km; Fig. 8a ). Above the maximum of latent heating, PV is diabatically reduced, and

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