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Chenjie Huang, Y-L. Lin, M. L. Kaplan, and J. J. Charney

fires developed as a result of the coupling of the synoptic-scale and mesoscale processes. The polar jet streak upstream of the upper-level trough over the north-central United States strengthened from 0000 UTC 25 October to 1200 UTC 26 October 2003 and evolved from a straight jet into a more anticyclonically curved jet ( Figs. 10a and 10b ). The increase in curvature has an important impact on the force balance that an air parcel may experience when passing through the jet streak; that is, the

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Andrew J. Majda

; Hendon and Salby 1994 ). Futhermore, recent processing of observational data ( Mapes et al. 2006 ) suggests the statistical self-similarity of tropical convection on multiple spatiotemporal scales ranging from the mesoscales to the planetary scales. On the other hand, contemporary general circulation models (GCMs) perform poorly both in their ability to resolve convectively coupled synoptic-scale waves and the MJO ( Slingo et al. 1996 ; Lin et al. 2006 ). One conjectured reason for this inadequate

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Trevor Mitchell and David M. Schultz

the magnitude of moisture detrainment can also be affected by large-scale processes. Schultz et al. (2007) showed that synoptic-scale processes are important in regulating the strength of the dryline. Stronger drylines were associated with passage of a short-wave trough in the ambient westerlies, favoring surface cyclogenesis, increased confluence, and tighter moisture gradients. Short-wave troughing may also increase the likelihood of convection given the presence of a dryline. Rhea (1966

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Yu-Ming Tsai, Hung-Chi Kuo, and Wayne H. Schubert

selective decay process is associated with vortex mergers within a sea of filamentary structures produced by earlier vortex interactions. At the mesoscale, spiral rainbands and their associated PV structures are one of the most noticeable features associated with tropical cyclones ( Guinn and Schubert 1993 ). At the synoptic scale, trough-thinning phenomena are common in midlatitude baroclinic waves ( Keyser and Shapiro 1986 ; Thorncroft et al. 1993 , hereinafter THM ; Appenzeller et al. 1996 ; Kunz

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David M. Schultz, Christopher C. Weiss, and Paul M. Hoffman

conceptual model begs the following two questions: What processes control the strength of the dryline? Is convection initiation related to the strength of the dryline? The present paper addresses the first question by examining the synoptic-scale influences on dryline intensity. A future paper will address the second question. Finescale mobile surface observations (e.g., Ziegler and Hane 1993 ; Ziegler and Rasmussen 1998 ) and aircraft observations (e.g., Geerts et al. 2006 ) show that the width of

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Gwendal Rivière

weather regimes into different configurations of the effective deformation field at 300 hPa. In the same section, a statistical analysis of the barotropic regeneration process about a BtCR is described. In section 4 , numerical experiments in a forced barotropic model on the sphere are performed. Each experiment consists of adding a synoptic-scale perturbation initially to one of the zonal-like jet configurations found in section 3 that is maintained fixed during the whole simulation. Section 4

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Troy R. Blandford, Karen S. Humes, Brian J. Harshburger, Brandon C. Moore, Von P. Walden, and Hengchun Ye

colder months partially explains the seasonal trend in lapse rates ( Whiteman et al. 1999 ). Several studies have investigated the impacts of synoptic weather conditions, or large-scale weather patterns, on lapse rates ( Pepin et al. 1999 ; Stahl et al. 2005 ). Pepin et al. (1999) conducted a study in the uplands of northern England evaluating the relationships between lapse rates and solar radiation, humidity, wind speed, and synoptic types. Steeper lapse rates occurred with higher levels of

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Sulian Thual, Andrew J. Majda, and Samuel N. Stechmann

inadequate treatment of the organized hierarchy of tropical processes as a whole (e.g., Hendon and Liebmann 1994 ; Zhang 2005 ; Moncrieff et al. 2007 ; Lau and Waliser 2012 ). This hierarchy involves interactions between organized structures of tropical convection (convectively coupled waves, cloud clusters, etc.) that are defined on a vast range of spatiotemporal scales (synoptic, mesoscale, etc.) and that generate the MJO as their planetary envelope. This organized hierarchy of tropical processes

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Yang Yang and X. San Liang

captures almost all the observed spectral peaks in the mesoscale (30–280 day) as well as longer (i.e., interannual and longer) time scales, albeit with a slightly weaker amplitude compared to that of the observations. An advantage of HYCOM over the altimeter data is that HYCOM includes high-frequency synoptic motions (defined as processes with periods shorter than 30 days in this study) which are largely absent in the current gridded altimeter products because of inherent filtering of the satellite

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Jingjie Yu, Bolan Gan, Zhao Jing, and Lixin Wu

temperature and salinity data from Argo profiling floats. This is consistent with the finding of Iwasaka et al. (2006) that the high-frequency fluctuations of MLD with period on the order of 10 days are presumed to be associated with the short-term variations of the net surface heat flux. Such a relationship, however, has not yet been fully established. Indeed, the observed heat and momentum fluxes in the western North Pacific have dominant synoptic time scales of 3–14 and 2–8 days, respectively ( Qiu

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