scholarly journals Future Changes of the Monsoon Trough: Sensitivity to Sea Surface Temperature Gradient and Implications for Tropical Cyclone Activity

2018 ◽  
Vol 6 (6) ◽  
pp. 919-936 ◽  
Author(s):  
Chao Wang ◽  
Liguang Wu
Keyword(s):  
Tropical Cyclone ◽  
Temperature Gradient ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Monsoon Trough ◽  
Tropical Cyclone Activity ◽  
Sea Surface ◽  
Cyclone Activity ◽  
Sea Surface Temperature Gradient ◽  
Surface Temperature Gradient

What Controls the Mean East–West Sea Surface Temperature Gradient in the Equatorial Pacific: The Role of Cloud Albedo

2014 ◽  
Vol 27 (7) ◽  
pp. 2757-2778 ◽  
Author(s):  
N. J. Burls ◽  
A. V. Fedorov
Keyword(s):  
Temperature Gradient ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Walker Circulation ◽  
Equatorial Pacific ◽  
Sea Surface ◽  
Sea Surface Temperature Gradient ◽  
The Mean ◽  
East West ◽  
Surface Temperature Gradient

Abstract The mean east–west sea surface temperature gradient along the equator is a key feature of tropical climate. Tightly coupled to the atmospheric Walker circulation and the oceanic east–west thermocline tilt, it effectively defines tropical climate conditions. In the Pacific, its presence permits the El Niño–Southern Oscillation phenomenon. What determines this temperature gradient within the fully coupled ocean–atmosphere system is therefore a central question in climate dynamics, critical for understanding past and future climates. Using a comprehensive coupled model [Community Earth System Model (CESM)], the authors demonstrate how the meridional gradient in cloud albedo between the tropics and midlatitudes (Δα) sets the mean east–west sea surface temperature gradient in the equatorial Pacific. To change Δα in the numerical experiments, the authors change the optical properties of clouds by modifying the atmospheric water path, but only in the shortwave radiation scheme of the model. When Δα is varied from approximately −0.15 to 0.1, the east–west SST contrast in the equatorial Pacific reduces from 7.5°C to less than 1°C and the Walker circulation nearly collapses. These experiments reveal a near-linear dependence between Δα and the zonal temperature gradient, which generally agrees with results from the Coupled Model Intercomparison Project phase 5 (CMIP5) preindustrial control simulations. The authors explain the close relation between the two variables using an energy balance model incorporating the essential dynamics of the warm pool, cold tongue, and Walker circulation complex.

scholarly journals The role of the meridional sea surface temperature gradient in controlling the Caribbean low‐level jet

2017 ◽  
Vol 122 (11) ◽  
pp. 5903-5916 ◽  
Author(s):  
Tito Maldonado ◽  
Anna Rutgersson ◽  
Rodrigo Caballero ◽  
Francesco S. R. Pausata ◽  
Eric Alfaro ◽  
...  
Keyword(s):  
Temperature Gradient ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Sea Surface ◽  
Low Level ◽  
Sea Surface Temperature Gradient ◽  
Low Level Jet ◽  
The Caribbean ◽  
Surface Temperature Gradient

scholarly journals On the Variability and Predictability of Eastern Pacific Tropical Cyclone Activity*

2015 ◽  
Vol 28 (24) ◽  
pp. 9678-9696 ◽  
Author(s):  
Louis-Philippe Caron ◽  
Mathieu Boudreault ◽  
Suzana J. Camargo
Keyword(s):  
Tropical Cyclone ◽  
Model Selection ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Heat Content ◽  
Tropical Cyclone Activity ◽  
Sea Surface ◽  
Eastern Pacific ◽  
Cyclone Activity ◽  
Wide Range

Abstract Variability in tropical cyclone activity in the eastern Pacific basin has been linked to a wide range of climate factors, yet the dominant factors driving this variability have yet to be identified. Using Poisson regressions and a track clustering method, the authors analyze and compare the climate influence on cyclone activity in this region. The authors show that local sea surface temperature and upper-ocean heat content as well as large-scale conditions in the northern Atlantic are the dominant influence in modulating eastern North Pacific tropical cyclone activity. The results also support previous findings suggesting that the influence of the Atlantic Ocean occurs through changes in dynamical conditions over the eastern Pacific. Using model selection algorithms, the authors then proceed to construct a statistical model of eastern Pacific tropical cyclone activity. The various model selection techniques used agree in selecting one predictor from the Atlantic (northern North Atlantic sea surface temperature) and one predictor from the Pacific (relative sea surface temperature) to represent the best possible model. Finally, we show that this simple model could have predicted the anomalously high level of activity observed in 2014.

scholarly journals The West Pacific Gradient tracks ENSO and zonal Pacific sea surface temperature gradient during the last Millennium

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
J. Zinke ◽  
S. A. Browning ◽  
A. Hoell ◽  
I. D. Goodwin
Keyword(s):  
Temperature Gradient ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
El Nino ◽  
Sea Surface ◽  
Last Millennium ◽  
The West ◽  
West Pacific ◽  
Sea Surface Temperature Gradient ◽  
Surface Temperature Gradient

AbstractSmall changes in Pacific temperature gradients connected with the El Niño Southern Oscillation (ENSO) influence the Walker Circulation and are related to global climate anomalies. Therefore, it is of paramount importance to develop robust indices of their past behavior. Here, we reconstruct the difference in sea surface temperature between the west and central Pacific during ENSO, coined the West Pacific Gradient (WPG), based on the Last Millennium Paleo Hydrodynamics Data Assimilation. We show that the WPG tracks ENSO variability and strongly co-varies with the zonal gradient in Pacific sea surface temperature. We demonstrate that the WPG strength is related to significant atmospheric circulation and precipitation anomalies during historical El Niño and La Niña events by magnifying or weakening droughts and pluvials across the Indo-Pacific. We show that an extreme negative WPG coupled to a strong zonal Pacific temperature gradient is associated with enhanced megadroughts in North America between 1400 CE and the late sixteenth century. The twentieth century stands out in showing the most extreme swings between positive and negative WPG conditions over the past Millennium. We conclude that the WPG is a robust index together with ENSO indices to reveal past changes in Pacific zonal sea surface temperature gradient variability.

scholarly journals The Roles of Wind Shear and Thermal Stratification in Past and Projected Changes of Atlantic Tropical Cyclone Activity

2009 ◽  
Vol 22 (17) ◽  
pp. 4723-4734 ◽  
Author(s):  
Stephen T. Garner ◽  
Isaac M. Held ◽  
Thomas Knutson ◽  
Joseph Sirutis
Keyword(s):  
Tropical Cyclone ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Tropical Cyclone Activity ◽  
Sea Surface ◽  
Vertical Shear ◽  
Cyclone Activity ◽  
Western Atlantic ◽  
Environmental Indices ◽  
Atlantic Tropical Cyclone

Abstract Atlantic tropical cyclone activity has trended upward in recent decades. The increase coincides with favorable changes in local sea surface temperature and other environmental indices, principally associated with vertical shear and the thermodynamic profile. The relative importance of these environmental factors has not been firmly established. A recent study using a high-resolution dynamical downscaling model has captured both the trend and interannual variations in Atlantic storm frequency with considerable fidelity. In the present work, this downscaling framework is used to assess the importance of the large-scale thermodynamic environment relative to other factors influencing Atlantic tropical storms. Separate assessments are done for the recent multidecadal trend (1980–2006) and a model-projected global warming environment for the late 21st century. For the multidecadal trend, changes in the seasonal-mean thermodynamic environment (sea surface temperature and atmospheric temperature profile at fixed relative humidity) account for more than half of the observed increase in tropical cyclone frequency, with other seasonal-mean changes (including vertical shear) having a somewhat smaller combined effect. In contrast, the model’s projected reduction in Atlantic tropical cyclone activity in the warm climate scenario appears to be driven mostly by increased seasonal-mean vertical shear in the western Atlantic and Caribbean rather than by changes in the SST and thermodynamic profile.

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