Explore the vast range of titles available.

Previous studies have documented an abrupt decrease of tropical cyclone (TC) genesis frequency over the western North Pacific (WNP) since 1998. In this study, results from an objective clustering analysis demonstrated that this abrupt decrease is primarily related to the decrease in a cluster of TCs (C1) that mostly formed over the southeastern WNP, south of 15°N and east of the Philippines, and possessed long tracks. Further statistical analyses based on both best track TC data and global reanalysis data during 1980–2015 revealed that the genesis of C1 TCs was significantly modulated by the interdecadal Pacific oscillation (IPO), whose recent negative phase since 1998 corresponded to a La Niña–like sea surface temperature anomaly (SSTA) pattern, which strengthened the Walker circulation in the tropical Pacific and weakened the WNP monsoon trough, suppressing genesis of C1 TCs in the southeastern WNP and predominantly contributing to the decrease in TC genesis frequency over the entire WNP basin. These findings were further confirmed by results from similar analyses based on longer observational datasets and also the outputs from a 500-yr preindustrial general circulation model experiment using the Geophysical Fluid Dynamics Laboratory (GFDL) Coupled Model, version 3. Additional analysis indicates that the decrease in C1 TC genesis frequency in the recent period was dominated during August–October, with the largest decrease in October.

Several studies have discussed the interannual influences of the North Pacific Meridional Mode (PMM) on the tropical cyclone (TC) in the western North Pacific (WNP). However, most of them either mixed the contributions of the PMM and Pacific decadal modes or failed to separate the PMM and El Niño-Southern Oscillation (ENSO) impacts. Here, we systematically revisited the year-to-year relationship between the PMM and WNP TC activity, including TC genesis frequency (TCGF) and TC track density (TCTD), by removing decadal variability. The results show that positive (negative) PMM events can induce anomalous basin-uniform cyclonic (anticyclonic) circulation and lead to a significant increase (decrease) in TCGF and TCTD over the WNP. The relationship between TCGF and the PMM is modulated by the ENSO events. When the positive PMM events are synchronized with the El Niño phase, they can enhance southeastern quadrant TC genesis over the WNP and increase TCTD in the whole WNP. However, when the positive PMM events are in phase with La Niña events, it shows an insignificant impact on WNP TCs due to the reverse influence of PMM and ENSO. This study emphasizes the important influence of the PMM on WNP TC activity on interannual time scale, especially during neutral ENSO years.

Arctic amplification caused by the rapid loss of Arctic sea ice has emerged as a crucial factor in affecting global weather and climate in recent decades. However, it remains unknown whether this rapid loss has exerted a specific impact on tropical cyclone (TC) activity over the eastern North Pacific (ENP). Here, we examine the influence of springtime (March–May) sea ice concentration (SIC) in the Barents Sea (SIC-BS), a key region for Arctic SIC changes, on TC genesis frequency over the ENP during the TC season (June–October) during 1970–2021. Results show that the reduced SIC-BS was favorable for more TC geneses over the ENP in terms of interannual variability. Further analyses based on dynamical diagnosis demonstrate that the rapid loss of SIC-BS leads to an upward transport of turbulent heat fluxes, facilitating the propagation of the Rossby wave train from the Barents Sea to the ENP via the western United States. This process subsequently leads to increase in upper-level divergence, mid-level upward motion, and lower-level vorticity, thereby accounting for the formation of more TCs over the ENP. This mechanism is further substantiated by the Coupled Model Intercomparison Project phase 6 (CMIP6). These results not only establish a possible connection between Arctic sea ice and tropical climate, but also hold important implications for understanding future changes in TC activity over the ENP.

The recent global warming hiatus (GWH) was characterized by a La Niña–like cooling in the tropical Eastern Pacific accompanied with the Indian Ocean and the tropical Atlantic Ocean warming. Here we show that the recent GWH contributed significantly to the increased occurrence of intense tropical cyclones in the coastal regions along East Asia since 1998. The GWH associated sea surface temperature anomalies triggered a pair of anomalous cyclonic and anticyclonic circulations and equatorial easterly anomalies over the Northwest Pacific, which favored TC genesis and intensification over the western Northwest Pacific but suppressed TC genesis and intensification over the southeastern Northwest Pacific due to increased vertical wind shear and anticyclonic circulation anomalies. Results from atmospheric general circulation model experiments demonstrate that the Pacific La Niña–like cooling dominated the Indian Ocean and the tropical Atlantic Ocean warming in contributing to the observed GWH-related anomalous atmospheric circulation over the Northwest Pacific.

A prominent feature of the western North Pacific tropical cyclone genesis frequency (TCGF) anomaly in response to El Niño‐Southern Oscillation (ENSO) is a distinct west‐east dipole structure in the present‐day (PD) climate. Here, large ensemble high‐resolution simulations show that the current dipole may transform into a monopole under global warming (GW). In the PD climate, the ENSO‐induced dipole effect on TCGF is mainly observed in late autumn. However, GW accelerates this effect into the summer by amplifying atmospheric circulation anomalies. Consequently, this leads to a significant increase in the coastal TCGF during the development phase of El Niño under GW. Meanwhile, it weakens the anomalous anticyclonic circulation during late autumn, leading to an increase in coastal TCGF during the mature phase of El Niño, and vice versa. Therefore, the combined effect suggests a potential trend toward spatial homogenization during ENSO phases under GW. Plain Language Summary El Niño‐Southern Oscillation (ENSO) typically has a dipole impact on tropical cyclone genesis frequency (TCGF) over the western North Pacific (WNP) in the current climate. During the warm phase of ENSO, there is a significant increase in TCGF over the southeastern part of the WNP (open‐sea region), but a decrease over its northwestern part (coastal region). The opposite pattern occurs during the cold phase of ENSO. However, under global warming (GW), this dipole pattern could transform into a basin‐uniform change in TCGF. In the present climate, ENSO primarily affects TCGF only over the open‐sea region during the summer (June to August) but causes a dipole pattern of TCGF anomalies in the autumn (September–November). The summer TCGF over the coastal region is less influenced by ENSO. Hence, the dipole pattern of TCGF anomalies from summer to autumn is mainly contributed by the anomaly in autumn TCGF over the coastal region. However, GW could extend the ENSO impact on coastal TCGF to summer. Therefore, the TCGF anomaly in summer offsets the opposite TCGF anomaly in autumn over the coastal region during the ENSO phase, resulting in a more consistent change in TCGF anomalies across the region under GW. Key Points The dipole pattern of tropical cyclone genesis frequency (TCGF) during June–November in response to El Niño‐Southern Oscillation (ENSO) over the western North Pacific may transform into a monopole under global warming (GW) The present‐day dipole of TCGF anomaly is mainly observed in late‐autumn, while GW accelerates this impact to summer GW amplifies cyclonic (anticyclonic) circulation during warm (cold) ENSO phases, causing a basin‐uniform TCGF change

Most previous studies have reported a decrease in global tropical cyclone (TC) genesis frequency (TCGF) under anthropogenic warming. However, little attention has been drawn to the influence of sea surface temperature (SST) warming patterns on TCGF changes. Here, we investigate the impacts of three distinct SST warming patterns on global TCGF: uniform SST warming, nonuniform (El Niño-like) SST warming, and a combination of both. Results show that spatio-uniform SST warming has a limited impact on global TCGF, instead redistributing the TC genesis locations. Conversely, nonuniform SST warming significantly suppresses global TCGF. The combined warming produces a similar decrease in TCGF to nonuniform warming albeit with differences in spatial distribution. This indicates the dominant role of nonuniform SST warming in affecting TCGF and highlights the nonlinearity of the process. Further analysis shows that these differences in TCGF primarily stem from the distinct responses of tropical circulations to the three warming patterns.

How future multiple tropical cyclone events (MTCEs) could change is crucial for effective risk management and ensuring human safety, however, it remains unclear. This study projects changes in MTCEs by 2050 in the major basins of the Northern Hemisphere using high‐resolution climate models. Results show a significant increase in the frequency and duration of MTCEs over the North Atlantic (NA), a notable decrease over the western North Pacific (WNP), and little change over the eastern North Pacific (ENP). The increase in MTCEs over the NA is concentrated in August–September, while the decrease over the WNP occurs in most months. In contrast, the ENP exhibits large yet insignificant seasonal variation, suggesting considerable uncertainty in this basin. Further analysis shows that mid‐level vertical motion dominates the MTCE changes over the WNP, while vertical wind shear contributes the most to the NA, which may be linked to future changes in tropical convection. Plain Language Summary Multiple tropical cyclone (TC) events (MTCEs), that is two or more TCs simultaneously occurring in the same basin, pose great risks to human society. This study projects future changes in the MTCEs by 2050, showing a significant increase over the North Atlantic (NA) while a robust reduction over the western North Pacific (WNP). The future MTCEs over the eastern North Pacific (ENP) show little change relative to the present climate. The increase of MTCEs over the NA is concentrated in August–September, while the decrease over the WNP occurs nearly from April to November. In contrast, there is large yet insignificant seasonal variation over the ENP, which could lead to little change in annual MTCEs. Furthermore, these changes are primarily attributed to the changes in local large‐scale dynamic conditions associated with tropical convection in future decades. Key Points The projection of future multiple tropical cyclone events (MTCEs) shows a decline in the western North Pacific (WNP) but a significant increase in the North Atlantic (NA) The mid‐level vertical motion dominates the MTCE changes over the WNP, while vertical wind shear is important for the NA Future monthly MTCEs show large yet insignificant seasonal variation over the eastern North Pacific, causing little trend in annual MTCEs

The June‐July Yangtze flooding in 1998 and 2020 drew incredible attention owing to the extreme precipitation events and devastating societal/economic damages. However, the quantitative estimation of the moisture transport mechanism is intensely discussed but still unresolved. Here we investigated two events from a unique perspective of Eulerian atmospheric water tracers that tries to explain the two events from model physics. The results showed that the moisture supplies from the Northwest Pacific decreased despite of different inducements, whereas the southwest summer monsoon (SWSM)‐related moisture supplies exhibited conspicuous enhancements in both events, suggesting that the SWSM‐related moisture supplies controlled the occurrence of Yangtze flooding. The physical processes of the two events were further compared. The 2020 flooding was more severe than the 1998 event, which was related to the stronger advective convergences and in‐stratus condensations of the SWSM‐related moisture. Plain Language Summary In 1998 and 2020, the Yangtze River valley experienced extreme rainfalls during June–July. The associated atmospheric river was detected to be significantly enhanced by the moisture from the southwest summer monsoon‐related source regions (such as the Bay of Bengal, Arabian Sea, Tropical Indian Ocean, Indo‐China Peninsula, and India) in both events. On the contrary, the moisture supplies from the Northwest Pacific declined. These results suggested that the southwest summer monsoon‐related moisture supplies played vital roles in the formations of extreme rainfalls over the Yangtze River valley. Additionally, our study investigated the differences in the physical mechanisms of the two extreme rainfall events. The stronger advective transport and cloud processes forced more southwest summer monsoon‐related moisture to be converted into precipitation around the Yangtze River, ultimately leading to more severe flooding in 2020 than in 1998. Key Points The southwest summer monsoon (SWSM)‐related moisture supplies regulate the emergence of the Yangtze flooding during June–July Along with the flooding appearances, the moisture supplies from the Northwest Pacific to the Yangtze River valley decrease Stronger advective transport and in‐stratus condensations of the SWSM‐related moisture avail the larger flooding in 2020 than in 1998

The landfalling tropical cyclone track density (LTD) in China has shown an overall decreasing trend over the western North Pacific (WNP) while revealing an increase along the coastal East China (CEC) in the past several decades. This study further elucidates that the long‐term LTD trend in the CEC exhibits a pronounced seasonal contrast that there is a significant increase from August to October, whereas a decline is observed from May to July. This seasonal reversal in the CEC LTD trend is attributed to the northward migration of an intensified diabatic heating source from May to October under global warming. This result is supported by a linear baroclinic model that incorporates realistic precipitation trends to parameterize diabatic heating over the WNP. Our finding underscores the critical role of local warming in modulating LTD trends, emphasizing its seasonal dependence rather than relying solely on sea surface temperature changes.

A typical El Niño event often results in suppressed tropical cyclone (TC) genesis frequency (TCGF) over the North Atlantic (NA) and a distinct northwest-southeast dipole pattern in TCGF anomaly over the western North Pacific (WNP). The 2023 saw a strong El Niño event but surprisingly active NA and suppressed WNP TC activities. Here, we present that these unprecedented deviations were driven by the record-warm NA, a record-breaking negative phase of the Pacific Meridional Mode (PMM), and background global warming. Results from high-resolution global model experiments demonstrate that extraordinary Atlantic warming dominated the increased NA TCGF and contributed equally with the PMM to the suppressed WNP TCGF, overshadowing El Niño’s impact. Global warming also contributed to the observed TCGF anomalies. Our findings demonstrate that the typical influence of strong El Niño events on regional TC activity could be markedly altered by other climate modes, highlighting the complexity of TC genesis in a warming world. The impact of the 2023 strong El Niño event on North Atlantic and Northwest Pacific tropical cyclone activity was lapsed by the record-warm tropical North Atlantic, the record-breaking negative Pacific Meridional Mode, and background global warming.