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Caio A. S. Coelho and Lisa Goddard

1. Introduction The majority of drought-related hazards and the attendant economic losses and mortality risks reside in the tropics ( Dilley et al. 2005 ). Changes in climate variability, including more frequent and damaging extreme events such as drought, is one of many anticipated impacts of climate change. Estimating how climate variability may change in a warmer world, and how that variability intersects with more slowly evolving climate change, is vitally important to climate risk

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Dargan M. W. Frierson

1. Introduction Our picture of the Tropics is continually changing with the addition of new observations in this relatively data-sparse region. Many of these recent observations have provided compelling empirical tests for the theoretically based aspects of convection schemes, and the choice of parameters therein. For instance, the study of Brown and Bretherton (1997) demonstrates the correlation between boundary layer moist static energy and free tropospheric temperature, as postulated in

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Michelle R. McCrystall, J. Scott Hosking, Ian P. White, and Amanda C. Maycock

tropical SST trends over the same period and concluded that the local geopotential height and surface temperature trends were a consequence of tropical SST trends. They posited a mechanism related to a poleward propagating Rossby wave train emanating from the tropical Pacific (also Trenberth et al. 2014 ). While the reanalysis trends in wave activity flux (WAF) shown by D14 also indicate a poleward propagating wave train from the tropics toward NCG, there were differences in the wave propagation

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Wataru Yanase, Hiroshi Niino, Kevin Hodges, and Naoko Kitabatake

autumn seasons in both hemispheres, there are two dominant regions of cyclone development in the tropics and extratropics. Over the warm oceans in the tropics, TCs develop through a positive feedback mechanism between vortex circulation and diabatic processes including condensational heating of cumulus convection and ocean surface heat fluxes. ( Ooyama 1969 ; Emanuel 1986 ; Smith 1997 ). On the other hand, within the large temperature gradient in the extratropics, ECs develop as a response to

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David W. Pierce, Tim P. Barnett, and Mojib Latif

Philander (1997) extended the isopycnal advection idea to a theory in which such anomalies play a key role in generating decadal-scale climate variability. Essentially, advection along isopycnals provides a decadal-scale delay, while amplification of advected thermal anomalies that reach the surface in the Tropics keeps the oscillations self-sustaining in the presence of noise and dissipation. The idea of a tropical–midlatitude connection via wave propagation was addressed by Lysne et al. (1997

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JOHN R. BENNETT and JOHN A. YOUNG

, the northward component of velocity. The equation is analyzed as an eigenvalue problem and solvednumerically for the free modes of the Tropics for the case with zero mean flow. These solutions are compared withsolutions that are forced at a boundary situated in mid-latitudes, for cases with and without a mean zonal flow. At "critical latitnde.s," the basic equation has a singularity (where the phase speed of a wave forced at theboundary is equal to the mean flow). The caw for forced motions is

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Tadashi Tsuyuki

NOVEMBER 1996 T S U Y U K I 2545Variational Data Assimilation in the Tropics Using Precipitation Data. Part II: 3D Mode~ TADASHI TSUYUKI *Department of Meteorology, The Florida State University, Tallahassee, Florida(Manuscript received 10 August 1995, in final form 2 November 1995)ABSTRACT A global primitive equation model is used to examine the performance of four

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Masakazu Taguchi

colder in an experiment for a NH winter-like situation when the convective heating placed on the equator forces equatorial Rossby waves in the deep tropics, thus inducing stronger equatorial upwelling. When the heating is placed off the equator at 15°N to mimic a NH summerlike condition, the response is characterized by a dominant monsoon pattern in the subtropics. In contrast, a further observational analysis by Randel et al. (2008) using the National Centers of Environmental Prediction (NCEP

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Hella Garny, Martin Dameris, William Randel, Greg E. Bodeker, and Rudolf Deckert

trace gases with tropospheric sources therefore depend on the strength of the upwelling ( Holton et al. 1995 ). Because changes in tropical upwelling can induce trends in stratospheric composition, it is important to understand how tropical upwelling might be influenced by changes in climate. Upwelling in the tropics, forced by extratropical waves, constitutes the equatorial branch of the BDC ( Holton et al. 1995 ; Haynes et al. 1991 ). However, extratropical wave forcing alone cannot account for

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Zhengzhao Luo, Dieter Kley, Richard H. Johnson, and Herman Smit

van Velthoven (1997) and Ovarlez et al. (2000) focused on the modes (i.e., dry and moist conditions) whereas Oikonomou and O’Neill (2006) looked at the means. Since UTWV often shows bimodal distribution ( Zhang et al. 2003 ; Part I ), especially over the tropics, the bulk mean usually lies between the two modes. Similar means can be obtained through very different combinations of the modes. A more desirable approach would therefore be to study entire probability density functions (PDFs

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