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William J. Randel
,
Rolando Garcia
, and
Fei Wu

1. Introduction The general circulation of the stratosphere is characterized by a global overturning circulation with upwelling in the tropics and poleward–downward flow in the extratropics. This so-called Brewer–Dobson circulation was postulated based on observations of stratospheric water vapor ( Brewer 1949 ) and ozone ( Dobson 1956 ) and later confirmed from calculations of diabatic circulations in the stratosphere (e.g., Murgatroyd and Singleton 1961 ; Gille et al. 1987 ). This

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Peng Wang
,
James C. McWilliams
,
Dongxiao Wang
, and
Daling Li Yi

1. Introduction Upwelling refers to an upward movement of seawater and has a typical speed of 10 −6 –10 −4 m s −1 ( Hu and Wang 2016 ). Upwelling brings deep, cold, and nutrient-rich water to the euphotic zone from depths, enhancing biological primary productivity ( Kämpf and Chapman 2016 ; Largier 2020 ). Hence, typical upwelling regions have features of low sea surface temperature and high chlorophyll. Upwelling in the coastal ocean is commonly generated by alongshore winds that

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David Rivas
and
R. M. Samelson

1. Introduction Wind-driven upwelling is one of the most important processes affecting the coastal circulation off Oregon, and a critical factor in regional biological productivity and ecosystem structure. The upwelling season begins with the “spring transition,” when northward winds switch to southward, upwelling-favorable winds, and extends through the summer, typically until late fall ( Huyer 1983 ). The timing of the spring transition and the strength of the upwelling winds both show

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Yu-Lin Chang
,
Lie-Yauw Oey
,
Chau-Ron Wu
, and
Hung-Fu Lu

after the prevailing wind changed from southwesterly to northeasterly. The authors noted that upwelling brought nutrient-rich Kuroshio water onto the continental shelf. Wong et al. (2004) also reported upwelling at the shelf edge based on temperature and nitrate observations along a transect (their section E) on the northern shelf of Taiwan (near the section shown in Fig. 1 ). The authors did not examine the wind conditions, but we checked the wind at Pen-Chia Yu (PCY) ( Fig. 2 ) and found that

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Zhaoyun Chen
,
Yuwu Jiang
,
Jia Wang
, and
Wenping Gong

1. Introduction Nutrients are brought to the euphotic zone from deep water by the coastal upwelling processes. As the primary productivity is enhanced in the upwelling region, upwelling dynamics and the associated biological bloom have received extensive attention (e.g., Estrade et al. 2008 ; Lu et al. 2015 ). Upwelling regions with low temperature and high levels of nutrients often extend 200–300 km offshore in eastern boundary upwelling systems ( Messié et al. 2009 ; Chen et al. 2012

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Trevor J. McDougall
and
Raffaele Ferrari

Microstructure observations in the Brazil basin have shown that small-scale turbulent mixing in the abyssal ocean is bottom intensified, implying that the dianeutral velocity in the stratified interior ocean is directed downward. Polzin et al. (1997) , St. Laurent et al. (2001) , and de Lavergne et al. (2016) realized that the zero flux condition at the sloping sea floor implies that there must be dianeutral upwelling in a bottom boundary layer. Klocker and McDougall (2010) considered the

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Yiwen Pan
,
Yifan Li
,
Wei Fan
,
Dahai Zhang
,
Yongfa Qiang
,
Zong-Pei Jiang
, and
Ying Chen

great pressures and concerns on the problems of ocean fish stocks and human-driven climate change ( Lovelock and Rapley 2007 ; Kirke 2003 ). Artificial upwelling (AU) could bring cold, nutrient-rich, deep ocean water (DOW) to the euphotic zone, which could supplement and adjust the essential macro- and micronutrients concentrations. AU is considered as one of the geoengineering techniques that could potentially increase the marine fish productivity and probably accelerate the transfer of CO 2 to

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Marvin A. Geller
,
Tiehan Zhou
, and
Kevin Hamilton

1. Introduction The early works of Brewer (1949) and Dobson (1956) indicate that essentially all tropospheric air entering the stratosphere must do so through upwelling in the tropics. Although some tropospheric air can enter the stratosphere through isentropic transport at higher latitudes, this air is subsequently transported down back into the troposphere by the large-scale Brewer–Dobson circulation and, thus, does not reach the chemically active region above 100 hPa ( Rosenlof and

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Rei Ueyama
and
John M. Wallace

to a distinctive “tropical cold point” just above the 100-hPa level with temperatures on the order of −80°C. The rate of tropical upwelling, or the strength of the BDC, determines the tropical cold point temperature and consequently the water vapor mixing ratio of the “freeze-dried” air entering the stratosphere. It also controls the concentrations of long-lived chemical species of tropospheric origin in the lower stratosphere. The existence of pronounced annual cycles in tropical cold point

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

1. Introduction Many model studies have projected a strengthening of the Brewer–Dobson circulation (BDC), and in particular of tropical upwelling in the lower stratosphere, under increased atmospheric greenhouse gas (GHG) loading ( Butchart et al. 2006 ; Garcia and Randel 2008 ; Deckert and Dameris 2008 ; McLandress and Shepherd 2009 ). Upwelling across the tropical tropopause is the main pathway for tropospheric air masses entering the stratosphere. Stratospheric concentrations of many

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