The Influence of Large-Scale Environment on the Extremely Active Tropical Cyclone Activity in November 2019 over the Western North Pacific
In November 2019, tropical cyclone (TC) frequency over the western North Pacific reached its record high. In this study, the possible causes and formation mechanisms of that record high TC frequency are investigated by analyzing the effect of large-scale environmental factors. A comparison between t...
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doaj-f66de3ff188345a59dc6fb19f43bc4852021-04-15T23:06:17ZengMDPI AGAtmosphere2073-44332021-04-011250150110.3390/atmos12040501The Influence of Large-Scale Environment on the Extremely Active Tropical Cyclone Activity in November 2019 over the Western North PacificMengying Shi0Sulei Wang1Xiaoxu Qi2Haikun Zhao3Yu Shu4School of Atmospheric Sciences, Nanjing University of Information Science & Technology, Nanjing 210044, ChinaSchool of Atmospheric Sciences, Nanjing University of Information Science & Technology, Nanjing 210044, ChinaSchool of Atmospheric Sciences, Nanjing University of Information Science & Technology, Nanjing 210044, ChinaSchool of Atmospheric Sciences, Nanjing University of Information Science & Technology, Nanjing 210044, ChinaNanjing Meteorological Bureau, Nanjing 210019, ChinaIn November 2019, tropical cyclone (TC) frequency over the western North Pacific reached its record high. In this study, the possible causes and formation mechanisms of that record high TC frequency are investigated by analyzing the effect of large-scale environmental factors. A comparison between the extremely active TC years and extremely inactive TC years is performed to show the importance of the large-scale environment. The contributions of several dynamic and thermodynamic environmental factors are examined on the basis of two genesis potential indexes and the box difference index that can measure the relative contributions of large-scale environmental factors to the change in TC genesis frequency. Results indicate that dynamical factors played a more important role in TC genesis in November 2019 than thermodynamic factors. The main contributions were from enhanced low-level vorticity and strong upward motion accompanied by positive anomalies in local sea surface temperature, while the minor contribution was from changes in vertical wind shear. Changes in these large-scale environmental factors are possibly related to sea surface temperature anomalies over the Pacific (e.g., strong Pacific meridional mode)<b>.</b>https://www.mdpi.com/2073-4433/12/4/501tropical cycloneswestern North Pacificgenesis potential indexlarge-scale factors |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Mengying Shi Sulei Wang Xiaoxu Qi Haikun Zhao Yu Shu |
spellingShingle |
Mengying Shi Sulei Wang Xiaoxu Qi Haikun Zhao Yu Shu The Influence of Large-Scale Environment on the Extremely Active Tropical Cyclone Activity in November 2019 over the Western North Pacific Atmosphere tropical cyclones western North Pacific genesis potential index large-scale factors |
author_facet |
Mengying Shi Sulei Wang Xiaoxu Qi Haikun Zhao Yu Shu |
author_sort |
Mengying Shi |
title |
The Influence of Large-Scale Environment on the Extremely Active Tropical Cyclone Activity in November 2019 over the Western North Pacific |
title_short |
The Influence of Large-Scale Environment on the Extremely Active Tropical Cyclone Activity in November 2019 over the Western North Pacific |
title_full |
The Influence of Large-Scale Environment on the Extremely Active Tropical Cyclone Activity in November 2019 over the Western North Pacific |
title_fullStr |
The Influence of Large-Scale Environment on the Extremely Active Tropical Cyclone Activity in November 2019 over the Western North Pacific |
title_full_unstemmed |
The Influence of Large-Scale Environment on the Extremely Active Tropical Cyclone Activity in November 2019 over the Western North Pacific |
title_sort |
influence of large-scale environment on the extremely active tropical cyclone activity in november 2019 over the western north pacific |
publisher |
MDPI AG |
series |
Atmosphere |
issn |
2073-4433 |
publishDate |
2021-04-01 |
description |
In November 2019, tropical cyclone (TC) frequency over the western North Pacific reached its record high. In this study, the possible causes and formation mechanisms of that record high TC frequency are investigated by analyzing the effect of large-scale environmental factors. A comparison between the extremely active TC years and extremely inactive TC years is performed to show the importance of the large-scale environment. The contributions of several dynamic and thermodynamic environmental factors are examined on the basis of two genesis potential indexes and the box difference index that can measure the relative contributions of large-scale environmental factors to the change in TC genesis frequency. Results indicate that dynamical factors played a more important role in TC genesis in November 2019 than thermodynamic factors. The main contributions were from enhanced low-level vorticity and strong upward motion accompanied by positive anomalies in local sea surface temperature, while the minor contribution was from changes in vertical wind shear. Changes in these large-scale environmental factors are possibly related to sea surface temperature anomalies over the Pacific (e.g., strong Pacific meridional mode)<b>.</b> |
topic |
tropical cyclones western North Pacific genesis potential index large-scale factors |
url |
https://www.mdpi.com/2073-4433/12/4/501 |
work_keys_str_mv |
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