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Qi Hu, Y. Tawaye, and S. Feng

extratropics, we also examine energetics in three different latitudinal bands, the Tropics, the midlatitudes, and the high latitudes, and their contributions to changes of the hemispheric energetics. The energetics are further examined in wavenumber domain for different waves in the atmosphere representing planetary, synoptic, and storm-scale circulations. A summary of this study is presented in section 4 along with a discussion on manifestation of changes of the atmospheric energetics in intensity and

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Buwen Dong and Paul J. Valdes

from the CLIMAP dataset. The other computed SSTs using a thermodynamic slab ocean model with prescribed ocean heat transport. Emphasis was given to the changes in midlatitude transient eddy activities and in planetary waves and their role in regional climate changes at LGM. Many previous studies suggest the importance of horizontal resolution on the simulation of present-day climate ( Boer and Lazare 1988 ; Boyle 1993 ; Deque et al. 1994 ; Phillips et al. 1995 ; Williamson et al. 1995 ) and on

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Wanying Kang and Eli Tziperman

model. Part I: Comparison with observations and an atmosphere-only GCM . J. Climate , 16 , 345 – 364 , doi: 10.1175/1520-0442(2003)016<0345:SOTMJO>2.0.CO;2 . 10.1175/1520-0442(2003)016<0345:SOTMJO>2.0.CO;2 Jones , C. , and L. M. V. Carvalho , 2006 : Changes in the activity of the Madden–Julian Oscillation during 1958–2004 . J. Climate , 19 , 6353 – 6370 , doi: 10.1175/JCLI3972.1 . 10.1175/JCLI3972.1 Karoly , D. , and B. Hoskins , 1982 : Three dimensional propagation of planetary

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Kevin E. Trenberth and Grant W. Branstator

to the atmosphere. The distribution of diagnosedheating anomalies over North America, together with a planetary wave model response to idealized forcing, isdescribed to clarify the possible role of soil moisture anomalies in perpetuating the drought. It is argued thatfeedback-caused soil moisture anomalies may have been secondary sources for the drought circulation but couldnot have been the primary instigator. For the most part, other diagnosed heating anomalies during the droughtare found to

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T. P. Barnett, M. Latif, E. Kirk, and E. Roeckner

importantin the planetary boundary layer in forcing the wind field convergence but not so important to the main troposphere,which is heated largely by condensation heating. The monopole response seen in the atmosphere above about500 mb is due to a combination of factors, the most important being adiabatic heating associated with subsidenceand tropic-wide variations in precipitation. The models show the role of air-sea heat exchange in the ocean heat balance in the wave guide is one ofdissipation

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Joshua Talib, Christopher M. Taylor, Anmin Duan, and Andrew G. Turner

temperature anomaly across western North America increases surface SHF and induces a positive midtropospheric geopotential anomaly, the development of a planetary wave train, a cyclonic anomaly over the southern Great Plains, and the favoring of positive boreal summer rainfall anomalies ( Xue et al. 2016 , 2018 ). Similar to mountainous regions in western North America, the TP is also a high elevated region at a similar latitude to the subtropical jet. It is hypothesized that mechanisms responsible for

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Xianan Jiang, Tim Li, and Bin Wang

Asian monsoon region. An open question is what causes the northward propagation of the BSISO convection in the monsoon region. Webster (1983) hypothesized that the land surface heat flux into the atmospheric planetary boundary layer (PBL) may play a role in destabilizing the atmosphere ahead of the convection, leading to a northward shift of the convective zone. However, observations show that the strongest northward propagation signal appears over the northern Indian Ocean (along Bay of Bengal

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Margaret A. Rozendaal, Conway B. Leovy, and Stephen A. Klein

flow, or westwardand equatorward, of the subtropical maxima in low-cloud fraction. This is qualitatively consistent with controlof the cloud amount by two competing processes in a partially decoupled cloud-topped planetary boundarylayer: heating by solar radiation absorption and advection of moist boundary layer air. A radiative transfer codehas been used to show that in eastern subtropical ocean regions, where the diurnal cycle of low clouds is largeand the cloud has a small optical thickness

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S. P. Hayes, M. J. McPhaden, and J. M. Wallace

in the space domain, which removes planetary-scale wind fluctuationsthat are unrelated to the local SST perturbations. The wind fluctuations observed in association with tropicalinstability waves are on the order of 1-2 m s-I. These results indicate that SST variability on weekly to monthly time scales forces perturbations in the surfacewind field. It is suggested that the principal coupling mechanism in this region is the modification of theatmospheric boundary layer stratification. Over the

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John D. Farrara and Jin-Yi Yu

this type of forcing ( Deser and Blackmon 1993 ). The second class is related to internal dynamical processes in the atmosphere. In this class, variations are produced without any variations in the external forcing. Interactions among different components of the atmospheric circulation (tropical–extratropical or wave–mean flow interactions) cause the circulation to vacillate between different regimes (e.g., Charney and DeVore 1979 ; Yu and Hartmann 1993 ). For the extratropical winter circulation

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