Impacts of the two types of El Niño on Pacific tropical cyclone activity

2015 ◽  
Vol 14 (2) ◽  
pp. 191-198 ◽  
Author(s):  
Shibin Xu ◽  
Fei Huang
Keyword(s):  
Tropical Cyclone ◽  
El Niño ◽  
El Nino ◽  
Tropical Cyclone Activity ◽  
Cyclone Activity

scholarly journals Multi-scale meteorological conceptual analysis of observed active fire hotspot activity and smoke optical depth in the Maritime Continent

2012 ◽  
Vol 12 (4) ◽  
pp. 2117-2147 ◽  
Author(s):  
J. S. Reid ◽  
P. Xian ◽  
E. J. Hyer ◽  
M. K. Flatau ◽  
E. M. Ramirez ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
Optical Depth ◽  
El Niño ◽  
El Nino ◽  
Tropical Cyclone Activity ◽  
Seasonal Migration ◽  
Cyclone Activity ◽  
Maritime Continent ◽  
El Niño Modoki ◽  
Active Fire

Abstract. Much research and speculation exists about the meteorological and climatological impacts of biomass burning in the Maritime Continent (MC) of Indonesia and Malaysia, particularly during El Nino events. However, the MC hosts some of the world's most complicated meteorology, and we wish to understand how tropical phenomena at a range of scales influence observed burning activity. Using Moderate Resolution Imaging Spectroradiometer (MODIS) derived active fire hotspot patterns coupled with aerosol data assimilation products, satellite based precipitation, and meteorological indices, the meteorological context of observed fire prevalence and smoke optical depth in the MC are examined. Relationships of burning and smoke transport to such meteorological and climatic factors as the interannual El Nino-Southern Oscillation (ENSO), El Nino Modoki, Indian Ocean Dipole (IOD), the seasonal migration of the Intertropical Convergence Zone, the 30–90 day Madden Julian Oscillation (MJO), tropical waves, tropical cyclone activity, and diurnal convection were investigated. A conceptual model of how all of the differing meteorological scales affect fire activity is presented. Each island and its internal geography have different sensitivities to these factors which are likely relatable to precipitation patterns and land use practices. At the broadest scales as previously reported, we corroborate ENSO is indeed the largest factor. However, burning is also enhanced by periods of El Nino Modoki. Conversely, IOD influences are unclear. While interannual phenomena correlate to total seasonal burning, the MJO largely controls when visible burning occurs. High frequency phenomena which are poorly constrained in models such as diurnal convection and tropical cyclone activity also have an impact which cannot be ignored. Finally, we emphasize that these phenomena not only influence burning, but also the observability of burning, further complicating our ability to assign reasonable emissions.

scholarly journals Multi-scale meteorological conceptual model of observed active fire hotspot activity and smoke optical depth in the Maritime Continent

2011 ◽  
Vol 11 (7) ◽  
pp. 21091-21170 ◽  
Author(s):  
J. S. Reid ◽  
P. Xian ◽  
E. J. Hyer ◽  
M. K. Flatau ◽  
E. M. Ramirez ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
Conceptual Model ◽  
Optical Depth ◽  
El Niño ◽  
El Nino ◽  
Tropical Cyclone Activity ◽  
Cyclone Activity ◽  
Maritime Continent ◽  
El Niño Modoki ◽  
Active Fire

Abstract. Much research and speculation exists about the meteorological and climatological impacts of biomass burning in the Maritime Continent (MC) of Indonesia and Malaysia, particularly during El Niño events. However, the MC hosts some of the world's most complicated meteorology, and we wish to understand how tropical phenomena at a range of scales influence observed burning activity. Using Moderate Resolution Imaging Spectroradiometer (MODIS) derived active fire hotspot patterns coupled with aerosol data assimilation products, satellite based precipitation, and meteorological indices, the meteorological context of observed fire prevalence and smoke optical depth in the MC are examined. Relationships of burning and smoke transport to such meteorological and climatic factors as the interannual El Niño-Southern Oscillation (ENSO), El Niño Modoki, Indian Ocean Dipole (IOP), the seasonal migration of the Intertropical Convergence Zone, the 30–90 day Madden Julian Oscillation (MJO), tropical waves, tropical cyclone activity, and diurnal convection were investigated. A conceptual model of how all of the differing meteorological scales affect fire activity is presented. Each island and its internal geography have different sensitivities to these factors which are likely relatable to precipitation patterns and land use practices. At the broadest scales as previously reported, we confirm ENSO is indeed the largest factor. However, burning is also enhanced by periods of El Niño Modoki. Conversely IOD influences are unclear. While interannual phenomena correlate to total seasonal burning, the MJO largely controls when visible burning occurs. High frequency phenomena which are poorly constrained in models such as diurnal convection and tropical cyclone activity also have an impact which cannot be ignored. Finally, we emphasize that these phenomena not only influence burning, but also the observability of burning, further complicating our ability to assign reasonable emissions.

scholarly journals The Impact of the El Niño–Southern Oscillation and Atlantic Meridional Mode on Seasonal Atlantic Tropical Cyclone Activity

2014 ◽  
Vol 27 (14) ◽  
pp. 5311-5328 ◽  
Author(s):  
Christina M. Patricola ◽  
R. Saravanan ◽  
Ping Chang
Keyword(s):  
Tropical Cyclone ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Tropical Cyclone Activity ◽  
Tropical Atlantic ◽  
Cyclone Activity ◽  
The Impact ◽  
Atlantic Meridional Mode ◽  
Atlantic Tropical Cyclone

Abstract Atlantic tropical cyclone (TC) activity is influenced by interannual tropical Pacific sea surface temperature (SST) variability characterized by the El Niño–Southern Oscillation (ENSO), as well as interannual-to-decadal variability in the interhemispheric gradient in tropical Atlantic SST characterized by the Atlantic meridional mode (AMM). Individually, the negative AMM phase (cool northern and warm southern tropical Atlantic SST anomalies) and El Niño each inhibit Atlantic TCs, and vice versa. The impact of concurrent strong phases of the ENSO and AMM on Atlantic TC activity is investigated. The response of the atmospheric environment relevant for TCs is evaluated with a genesis potential index. Composites of observed accumulated cyclone energy (ACE) suggest that ENSO and AMM can amplify or dampen the influence of one another on Atlantic TCs. To support the observational analysis, numerical simulations are performed using a 27-km resolution regional climate model. The control simulation uses observed SST and lateral boundary conditions (LBCs) of 1980–2000, and perturbed experiments are forced with ENSO phases through LBCs and eastern tropical Pacific SST and AMM phases through Atlantic SST. Simultaneous strong El Niño and strongly positive AMM, as well as strong concurrent La Niña and negative AMM, produce near-average Atlantic ACE suggesting compensation between the two influences, consistent with the observational analysis. Strong La Niña and strongly positive AMM together produce extremely intense Atlantic TC activity, supported largely by above average midtropospheric humidity, while strong El Niño and negative AMM together are not necessary conditions for significantly reduced Atlantic tropical cyclone activity.

ENSO-Modulated Cyclogenesis over the Bay of Bengal*

2013 ◽  
Vol 26 (24) ◽  
pp. 9806-9818 ◽  
Author(s):  
Clifford S. Felton ◽  
Bulusu Subrahmanyam ◽  
V. S. N. Murty
Keyword(s):  
Tropical Cyclone ◽  
Relative Humidity ◽  
El Niño ◽  
El Nino ◽  
Tropical Cyclone Activity ◽  
La Niña ◽  
Sea Surface ◽  
Cyclone Activity ◽  
La Nina ◽  
Sst Anomalies

Abstract The role of the El Niño–Southern Oscillation (ENSO) on the modulation of tropical cyclone activity over the Bay of Bengal (BoB) for the 1979–2011 period is examined. It is shown that Niño-3.4 sea surface temperature (SST) anomalies are negatively correlated with the BoB tropical cyclone activity to a statistically significant percentage by a lead time of 5 months. Composites of 10-m zonal winds exhibit greater variance during La Niña events, favoring the development of low-level cyclonic vorticity. Low vertical wind shear over the central and northern BoB also aids in the development of tropical cyclones during La Niña events. Increased relative humidity is the result of enhanced moisture transport and higher precipitable water under La Niña conditions. Furthermore, storm-relative composites of relative humidity show stronger moisture pulses over the BoB during La Niña. The enhanced moisture associated with tropical cyclogenesis likely aids in the development and strengthening of the systems. ENSO forces modulations in oceanic conditions as well. The observed negative (positive) SST anomalies during La Niña (El Niño) could be seen as the result of increased (decreased) net heat flux across the sea surface. Tropical cyclone activity varies between El Niño and La Niña as a result of anomalous wind and moisture patterns during each ENSO phase.

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