scholarly journals The Madden–Julian Oscillation’s Impacts on Worldwide Tropical Cyclone Activity

2014 ◽  
Vol 27 (6) ◽  
pp. 2317-2330 ◽  
Author(s):  
Philip J. Klotzbach
Keyword(s):  
Tropical Cyclone ◽  
Large Scale ◽  
Vertical Wind Shear ◽  
Vertical Motion ◽  
Tropical Cyclone Activity ◽  
Cyclone Activity ◽  
Sea Level Pressure ◽  
Tropical Cyclone Frequency ◽  
The Tropics ◽  
Cyclone Frequency

Abstract The 30–60-day Madden–Julian oscillation (MJO) has been documented in previous research to impact tropical cyclone (TC) activity for various tropical cyclone basins around the globe. The MJO modulates large-scale convective activity throughout the tropics, and concomitantly modulates other fields known to impact tropical cyclone activity such as vertical wind shear, midlevel moisture, vertical motion, and sea level pressure. The Atlantic basin typically shows the smallest modulations in most large-scale fields of any tropical cyclone basins; however, it still experiences significant modulations in tropical cyclone activity. The convectively enhanced phases of the MJO and the phases immediately following them are typically associated with above-average tropical cyclone frequency for each of the global TC basins, while the convectively suppressed phases of the MJO are typically associated with below-average tropical cyclone frequency. The number of rapid intensification periods are also shown to increase when the convectively enhanced phase of the MJO is impacting a particular tropical cyclone basin.

Climatic Shift of the Tropical Cyclone Activity Affecting Vietnam’s Coastal Region

2020 ◽  
Vol 59 (10) ◽  
pp. 1755-1768
Author(s):  
Duc Tran-Quang ◽  
Ha Pham-Thanh ◽  
The-Anh Vu ◽  
Chanh Kieu ◽  
Tan Phan-Van
Keyword(s):  
Tropical Cyclone ◽  
Wind Shear ◽  
Large Scale ◽  
Coastal Region ◽  
Vertical Wind Shear ◽  
Reanalysis Data ◽  
Tropical Cyclone Activity ◽  
Cyclone Activity ◽  
Consistent Increase ◽  
Recent Epoch

AbstractThis study examines the climatic shift of the tropical cyclone (TC) frequency affecting Vietnam’s coastal region during 1975–2014. By separating TC databases into two different 20-yr epochs, it is found that there is a consistent increase in both the number of strong TCs and the number of TC occurrences during the recent epoch (1995–2014) as compared with the reference epoch (1975–94) across different TC databases. This finding suggests that not only the number of strong TCs but also the lifetime of strong TCs affecting Vietnam’s coastal region has been recently increasing as compared with the reference epoch from 1975 to 1994. To understand the physical connection of these shifts in the TC frequency and duration, large-scale conditions obtained from reanalysis data are analyzed. Results show that meridional surface temperature gradient (STG) during the recent epoch is substantially larger than that during 1975–94. Such an increase in the meridional STG is important because it is potentially linked to the increase in large-scale vertical wind shear as well as the reduced intensity of summer monsoon in the South China Sea between the two epochs.

scholarly journals Response of Tropical Cyclones to Idealized Climate Change Experiments in a Global High-Resolution Coupled General Circulation Model

2013 ◽  
Vol 26 (20) ◽  
pp. 7966-7980 ◽  
Author(s):  
Ray Bell ◽  
Jane Strachan ◽  
Pier Luigi Vidale ◽  
Kevin Hodges ◽  
Malcolm Roberts
Keyword(s):  
High Resolution ◽  
Tropical Cyclone ◽  
Tropical Cyclones ◽  
General Circulation ◽  
Large Scale ◽  
Vertical Wind Shear ◽  
Circulation Model ◽  
Walker Circulation ◽  
Tropical Cyclone Activity ◽  
Cyclone Activity

Abstract The authors present an assessment of how tropical cyclone activity might change owing to the influence of increased atmospheric carbon dioxide concentrations, using the U.K. High-Resolution Global Environment Model (HiGEM) with N144 resolution (~90 km in the atmosphere and ~40 km in the ocean). Tropical cyclones are identified using a feature-tracking algorithm applied to model output. Tropical cyclones from idealized 30-yr 2×CO2 (2CO2) and 4×CO2 (4CO2) simulations are compared to those identified in a 150-yr present-day simulation that is separated into a five-member ensemble of 30-yr integrations. Tropical cyclones are shown to decrease in frequency globally by 9% in the 2CO2 and 26% in the 4CO2. Tropical cyclones only become more intense in the 4CO2; however, uncoupled time slice experiments reveal an increase in intensity in the 2CO2. An investigation into the large-scale environmental conditions, known to influence tropical cyclone activity in the main development regions, is used to determine the response of tropical cyclone activity to increased atmospheric CO2. A weaker Walker circulation and a reduction in zonally averaged regions of updrafts lead to a shift in the location of tropical cyclones in the Northern Hemisphere. A decrease in mean ascent at 500 hPa contributes to the reduction of tropical cyclones in the 2CO2 in most basins. The larger reduction of tropical cyclones in the 4CO2 arises from further reduction of the mean ascent at 500 hPa and a large enhancement of vertical wind shear, especially in the Southern Hemisphere, North Atlantic, and northeast Pacific.

On the Madden–Julian Oscillation–Atlantic Hurricane Relationship

2010 ◽  
Vol 23 (2) ◽  
pp. 282-293 ◽  
Author(s):  
Philip J. Klotzbach
Keyword(s):  
Tropical Cyclone ◽  
Relative Humidity ◽  
Gulf Of Mexico ◽  
Large Scale ◽  
Tropical Cyclone Activity ◽  
Tropical Atlantic ◽  
Madden Julian Oscillation ◽  
Cyclone Activity ◽  
Short Term ◽  
Potential Predictability

Abstract The large-scale equatorial circulation known as the Madden–Julian oscillation (MJO) has been shown to impact tropical cyclone activity in several basins around the globe. In this paper, the author utilizes an MJO index created by Wheeler and Hendon to examine its impacts on tropical genesis and intensification in the Atlantic. Large differences in frequency and intensity of tropical cyclone activity are seen, both in the tropical Atlantic as well as in the northwest Caribbean and Gulf of Mexico depending on the MJO phase. Coherent changes in upper- and lower-level winds and relative humidity are likely responsible for these differences. Since the MJO shows potential predictability out to about two weeks, the relationships discussed in this paper may be useful for short-term predictions of the probability of tropical cyclone activity in the Atlantic as a complement to the already available longer-term seasonal predictions.

scholarly journals The Combined QBO and ENSO Influence on Tropical Cyclone Activity over the North Atlantic Ocean

Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1588
Author(s):  
Alejandro Jaramillo ◽  
Christian Dominguez ◽  
Graciela Raga ◽  
Arturo I. Quintanar
Keyword(s):  
Tropical Cyclone ◽  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Deep Convection ◽  
Tropical Cyclone Activity ◽  
Tropical Convection ◽  
Tropopause Height ◽  
Cyclone Activity ◽  
The Tropics

The Quasi-Biennal Oscillation (QBO) and the El Niño-Southern Oscillation (ENSO) largely modulate the zonal wind in the tropics. Previous studies showed that QBO phases produce changes in deep convection through an increase/decrease in the tropopause height over the tropics and subtropics. This study investigates the combined effects of QBO and ENSO on tropical cyclone activity by modulating tropopause height. We found that tropopause height increases over the Gulf of Mexico, the Caribbean region, and the Western North Atlantic Ocean during La Niña + QBOW, allowing deeper tropical convection to develop over those regions. As a consequence, TC activity over those regions is not only increased in number but also enhanced in intensity. Conversely, during El Niño + QBOE, most deep tropical convection is inhibited over those same regions due to the decrease in tropopause height over the subtropics. We conclude that QBO effects on TCs and deep convection should be studied in combination with ENSO. Additional comparative studies using long record data at high vertical resolution are needed to fully understand to what extent QBO interacts with ENSO in the lower tropical stratosphere and upper tropical troposphere.

scholarly journals Multidecadal Variability in North Atlantic Tropical Cyclone Activity

2008 ◽  
Vol 21 (15) ◽  
pp. 3929-3935 ◽  
Author(s):  
Philip J. Klotzbach ◽  
William M. Gray
Keyword(s):  
Tropical Cyclone ◽  
North Atlantic ◽  
Tropical Cyclone Activity ◽  
Cyclone Activity ◽  
Sea Level Pressure ◽  
Atlantic Basin ◽  
Multidecadal Variability ◽  
The North ◽  
Sea Surface Temperature Anomalies ◽  
Using Data

Abstract Recent increases in Atlantic basin tropical cyclone activity since 1995 and the associated destructive U.S. landfall events in 2004 and 2005 have generated considerable interest into why there has been such a sharp upturn. Natural variability, human-induced global warming, or a combination of both factors, have been suggested. Several previous studies have discussed observed multidecadal variability in the North Atlantic over 25–40-yr time scales. This study, using data from 1878 to the present, creates a metric based on far North Atlantic sea surface temperature anomalies and basinwide North Atlantic sea level pressure anomalies that shows remarkable agreement with observed multidecadal variability in both Atlantic basin tropical cyclone activity and in U.S. landfall frequency.

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