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Alexander Ruzmaikin
,
Hartmut H. Aumann
, and
Evan M. Manning

( Waliser et al. 1993 ), the moisture of the upper troposphere and cloud-ice increase, driven by tropical deep convection. This effect greatly enhances the water vapor feedback ( Su et al. 2006 ), although no specific measure of its dependence on the surface temperature and humidity has been suggested. Clear-sky OLR data from the Earth Radiation Budget Experiment (ERBE) in 1985–88 were compared with outputs of the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4

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Lyubov G. Chumakova
,
Rodolfo R. Rosales
, and
Esteban G. Tabak

nonetheless the dynamical backbone of the troposphere. Yet discrete modes are the signature of systems of finite extent: a semi-infinite stratified atmosphere yields a continuum spectrum of modes, much as the Fourier transform in the infinite line, as opposed to the discrete Fourier series associated with finite intervals. This has led to arguments by R. Lindzen that these discrete tropospheric modes are just a fallacy of overly simplified theoretical models, and that the atmosphere “is characterized by a

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Pengcheng Zhang
and
Nicholas J. Lutsko

of the Rossby–Kelvin instability]. Equatorial superrotation can be further enhanced by a reduction in the breaking of baroclinic eddies originating in midlatitudes, which decelerates the flow in the tropics under Earthlike conditions ( Laraia and Schneider 2015 ; Polichtchouk and Cho 2016 ). On Earth, the stratosphere superrotates during the westerly phase of the quasi-biennial oscillation (QBO; see Baldwin et al. 2001 ), but the climatological winds of the troposphere do not superrotate. The

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Marie Lothon
,
Frédérique Saïd
,
Fabienne Lohou
, and
Bernard Campistron

convergence zone (ITCZ) that follows the apparent latitudinal movement of the sun ( Hastenrath 1995 ). This convergence and the differential surface heating between ocean and continent trigger and maintain the low-level humid monsoon flux from the Guinea Gulf. In opposition to the low-level southwesterly flow, a northeasterly advection (Harmattan) of a dry and warm Saharan air layer (SAL) develops in the mean troposphere sloping up the monsoon layer. The conflict of these two air masses of different

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David M. Romps
and
Zhiming Kuang

1. Introduction Despite decades of inquiry, the role of undiluted moist-adiabatic ascent in tropical oceanic deep convection remains a point of debate. Key aspects of the ongoing debate can be captured by four unanswered questions. The first is a simple question of existence: outside of tropical cyclones, do parcels of oceanic boundary layer air convect to the upper troposphere undiluted? The key word here is “undiluted,” as in not having entrained environmental air. Since this is a simple

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Judah Cohen
,
Mathew Barlow
,
Paul J. Kushner
, and
Kazuyuki Saito

1. Introduction In this report we examine the tropospheric precursors and horizontal structure of the multiple-week extratropical stratosphere–troposphere interaction events highlighted by Baldwin and Dunkerton (1999 , 2001 ) and numerous follow-on studies (e.g., Cohen et al. 2002 ; Baldwin et al. 2003 ; Polvani and Waugh 2004 ; Limpasuvan et al. 2004 , 2005 ; Reichler et al. 2005 ). These events consist of an annular-mode ( Thompson and Wallace 2000 ) signature that starts in the

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Xiaocen Shen
,
Lin Wang
,
Adam A. Scaife
,
Steven C. Hardiman
, and
Peiqiang Xu

1. Introduction The stratospheric polar vortex (SPV) is a unique circulation system in the extratropical stratosphere of both hemispheres that forms due to seasonal radiative cooling in winter ( Andrews et al. 1987 ). The variation of SPV is dynamically coupled to the troposphere from winter to spring via atmospheric waves ( Baldwin and Dunkerton 1999 , 2001 ; Waugh and Polvani 2010 ), among which the planetary-scale Rossby wave is essential ( Andrews et al. 1987 ). The variability of

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Robert X. Black
,
Brent A. McDaniel
, and
Walter A. Robinson

subject of considerable debate in the recent literature (e.g., Manzini et al. 2003 ). A robust bidirectional dynamical coupling between the stratosphere and troposphere has been observed in the boreal extratropics during winter ( Thompson and Wallace 1998 ; Baldwin et al. 2003 ; McDaniel and Black 2005 ) in association with intraseasonal variability in the northern annular mode (NAM). The NAM is the primary mode of circulation variability in the Northern Hemisphere extratropics and its lower

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Chengyang Zhang
,
Wenshou Tian
,
Jiankai Zhang
,
Tuantuan Zhang
,
Wei Yu
,
Song Yang
, and
Tao Wang

temperature (SST) ( Cui et al. 2015 ; Yu et al. 2021 ), and the South Asian high ( Wang and Guo 2012 ; Liu et al. 2017 ; Ge et al. 2018 ). In addition to the abovementioned signals, recent studies showed that the downward-extending stratospheric signals can also regulate the onset of Indian summer monsoon ( Ren and Hu 2014 ; Hu and Ren 2018 ). It has been revealed that the dynamic coupling between the stratosphere and the troposphere is closely related to the Arctic Oscillation (AO) that has a quasi

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Shu-Peng Ho
,
Ying-Hwa Kuo
, and
Sergey Sokolovskiy

1. Introduction Temperature and water vapor play a crucial role in weather and climate. Accurate global water vapor and temperature estimates, particularly in the middle and lower troposphere (LT), are extremely important for understanding the physics of convective cloud systems, precipitation, the hydrological cycle, and the energy balance of the earth ( Crook 1996 ; Lee et al. 1991 ; Mueller et al. 1993 ; Weckwerth et al. 1996 ; Webster and Stephens 1984 ). To more accurately assess

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