Behavior Of Tropical Cyclones Research Articles

DCMIP2016: the tropical cyclone test case

Abstract. This paper describes and analyzes the Reed–Jablonowski (RJ) tropical cyclone (TC) test case used in the 2016 Dynamical Core Model Intercomparison Project (DCMIP2016). This intermediate-complexity test case analyzes the evolution of a weak vortex into a TC in an idealized tropical environment. Reference solutions from nine general circulation models (GCMs) with identical simplified physics parameterization packages that participated in DCMIP2016 are analyzed in this study at 50 km horizontal grid spacing, with five of these models also providing solutions at 25 km grid spacing. Evolution of minimum surface pressure (MSP) and maximum 1 km azimuthally averaged wind speed (MWS), the wind–pressure relationship, radial profiles of wind speed and surface pressure, and wind composites are presented for all participating GCMs at both horizontal grid spacings. While all TCs undergo a similar evolution process, some reach significantly higher intensities than others, ultimately impacting their horizontal and vertical structures. TCs simulated at 25 km grid spacings retain these differences but reach higher intensities and are more compact than their 50 km counterparts. These results indicate that dynamical core choice is an essential factor in GCM development, and future work should be conducted to explore how specific differences within the dynamical core affect TC behavior in GCMs.

Poleward Migration of Spatial Asymmetry in Tropical Cyclone Precipitation over the Western North Pacific

Comprehensive understanding of the spatial characteristics of tropical cyclone (TC) precipitation is essential for effective socioeconomic planning and scientific research. The present study examines the spatial asymmetry in TC precipitation over the western North Pacific (WNP) concerning various factors, including latitudes, sea surface temperature (SST), TC intensity, and translation speed, based on satellite observations. The results reveal a significant poleward migration of TC precipitation asymmetry particularly above 15° N. Furthermore, the asymmetry exhibits considerable sensitivity to changes in TC center latitudes and SSTs, characterized by anticlockwise and northeastward migration, respectively. The poleward migration of TC precipitation spatial asymmetry is primarily due to the poleward decreasing SST, increasing vertical wind shear and increasing TC translation speed. These findings contribute to a comprehensive understanding of TC behavior over the WNP and provide valuable insights for disaster preparedness and mitigation efforts.

Structural Forecasting for Short-Term Tropical Cyclone Intensity Guidance

Abstract Because geostationary satellite (Geo) imagery provides a high temporal resolution window into tropical cyclone (TC) behavior, we investigate the viability of its application to short-term probabilistic forecasts of TC convective structure to subsequently predict TC intensity. Here, we present a prototype model that is trained solely on two inputs: Geo infrared imagery leading up to the synoptic time of interest and intensity estimates up to 6 h prior to that time. To estimate future TC structure, we compute cloud-top temperature radial profiles from infrared imagery and then simulate the evolution of an ensemble of those profiles over the subsequent 12 h by applying a deep autoregressive generative model (PixelSNAIL). To forecast TC intensities at hours 6 and 12, we input operational intensity estimates up to the current time (0 h) and simulated future radial profiles up to +12 h into a “nowcasting” convolutional neural network. We limit our inputs to demonstrate the viability of our approach and to enable quantification of value added by the observed and simulated future radial profiles beyond operational intensity estimates alone. Our prototype model achieves a marginally higher error than the National Hurricane Center’s official forecasts despite excluding environmental factors, such as vertical wind shear and sea surface temperature. We also demonstrate that it is possible to reasonably predict short-term evolution of TC convective structure via radial profiles from Geo infrared imagery, resulting in interpretable structural forecasts that may be valuable for TC operational guidance. Significance Statement This work presents a new method of short-term probabilistic forecasting for tropical cyclone (TC) convective structure and intensity using infrared geostationary satellite observations. Our prototype model’s performance indicates that there is some value in observed and simulated future cloud-top temperature radial profiles for short-term intensity forecasting. The nonlinear nature of machine learning tools can pose an interpretation challenge, but structural forecasts produced by our model can be directly evaluated and, thus, may offer helpful guidance to forecasters regarding short-term TC evolution. Since forecasters are time limited in producing each advisory package despite a growing wealth of satellite observations, a tool that captures recent TC convective evolution and potential future changes may support their assessment of TC behavior in crafting their forecasts.

Understanding the Variation and Mechanisms of Tropical Cyclone Genesis Potential over the Western North Pacific during the Past 20 000 Years

Abstract To deepen our understanding of the behavior of tropical cyclones (TCs) over the western North Pacific (WNP) and its response to various external forcings, we investigate the variation of TC genesis potential over the WNP during the past 20 ka that experienced several large forcings. Using a set of transient simulations and a genesis potential index, our results indicate that TC genesis potential in the storm season shows an overall increase averaged over the WNP during the Heinrich Stadial 1 (HS1; ∼17–16 ka) relative to the Last Glacial Maximum. Subsequently, there is a sharp decrease in genesis potential during the Bølling–Allerød (BA; ∼13.5 ka) relative to the HS1, which is followed by an increase during the Younger Dryas (YD; ∼12.9–11.7 ka). During the Holocene, TC genesis potential shows a slight decrease during the early–middle Holocene (∼11.7–6 ka) and a significant increasing trend afterward. Further analysis shows that the contribution of each genesis factor to the genesis potential change varies greatly with time, which is in turn tied to changes in external forcings. The increased meltwater fluxes dominate the increased genesis potential during the HS1 and YD, whereas all external forcings (i.e., changes in meltwater, ice sheets, CO2, and insolation) contribute to genesis potential change during the BA. The long-term increasing trend from the mid-Holocene to the present is controlled by orbital insolation. These results may help improve our understanding on past TC activity and shed lights on TC response to various external forcings in a long-term future.

A potential explanation for the global increase in tropical cyclone rapid intensification

Tropical cyclone rapid intensification events often cause destructive hurricane landfalls because they are associated with the strongest storms and forecasts with the highest errors. Multi-decade observational datasets of tropical cyclone behavior have recently enabled documentation of upward trends in tropical cyclone rapid intensification in several basins. However, a robust anthropogenic signal in global intensification trends and the physical drivers of intensification trends have yet to be identified. To address these knowledge gaps, here we compare the observed trends in intensification and tropical cyclone environmental parameters to simulated natural variability in a high-resolution global climate model. In multiple basins and the global dataset, we detect a significant increase in intensification rates with a positive contribution from anthropogenic forcing. Furthermore, thermodynamic environments around tropical cyclones have become more favorable for intensification, and climate models show anthropogenic warming has significantly increased the probability of these changes.

Application of the rotating-convection paradigm for tropical cyclones to interpreting medicanes: An example

The rotating-convection paradigm for tropical cyclone behaviour is shown to provide an attractive and consistent framework for interpreting the dynamics of formation and intensification of at least some medicanes. The ideas are illustrated by a case study of the medicane that formed over the eastern Mediterranean in mid-December 2020. This case study is based on analyses of data from the European Centre for Medium Range Weather Forecasts (ECMWF), imagery from the European geostationary meteorological satellite, Meteosat Second Generation, and output from a convection permitting numerical simulation of the event using the United Kingdom (UK) Met Office regional model with the RAL2 physics configuration. Limitations of the currently widely accepted interpretation of medicanes in terms of the so-called Wind-Induced Surface Heat Exchange (WISHE) intensification mechanism are discussed.

US Gulf Coast tropical cyclone precipitation influenced by volcanism and the North Atlantic subtropical high

Understanding the response of tropical cyclone precipitation to ongoing climate change is essential to determine associated flood risk. However, instrumental records are short-term and fail to capture the full range of variability in seasonal totals of precipitation from tropical cyclones. Here we present a 473-year-long tree-ring proxy record comprised of longleaf pine from excavated coffins, a historical house, remnant stumps, and living trees in southern Mississippi, USA. We use cross-dating dendrochronological analyses calibrated with instrumental records to reconstruct tropical cyclone precipitation stretching back to 1540 CE. We compare this record to potential climatic controls of interannual and multidecadal tropical cyclone precipitation variability along the Gulf Coast. We find that tropical cyclone precipitation declined significantly in the two years following large Northern Hemisphere volcanic eruptions and is influenced by the behavior of the North Atlantic subtropical high-pressure system. Additionally, we suggest that tropical cyclone precipitation variability is significantly, albeit weakly, related to Atlantic multidecadal variability. Finally, we suggest that we need to establish a network for reconstructing precipitation from tropical cyclones in the Southeast USA if we want to capture regional tropical cyclone behavior and associated flood risks.

Rising sea level and increasing tropical cyclone frequency are threatening the population of San Andrés Island, Colombia, western Caribbean

The Colombian island of San Andrés is a popular tourist destination located about 195 km offshore of the east coast of Nicaragua in the southwestern Caribbean Sea. Together with Providencia and Santa Catalina, San Andrés is part of the UNESCO Seaflower Biosphere Reserve. With a 26 km2 surface area and 78 000 inhabitants, San Andrés is one of the most densely populated islands in the Caribbean with on average ∼ 3000 inhabitants/km2. The majority of the population and the mass tourism are concentrated in the low-elevation (0.5–6 m) areas, particularly in the north and along the east coast of the island. These areas are prone to flooding during storm events such as hurricanes Eta and Iota in 2020. A review of the geological, environmental and the socio-economic situation of the island, and the record of tropical cyclones since 1911, shows why the local population has become increasingly vulnerable to storm events and rising sea level. Tropical cyclones may form locally in the southwestern Caribbean or originate in the eastern Caribbean/Atlantic Ocean. The latter tend to be stronger and cause more damage when they reach San Andrés. The HURDAT2 dataset shows that the frequency of storm events affecting San Andrés has increased in recent decades, with six storms over the past 20 years, including three category 4-5 hurricanes since 2007. Increasing storm frequency and intensity may be linked to increasing sea surface temperatures caused by anthropogenic global warming, although the changes described here may be limited to a relatively small geographical region, as opposed to representing basin wide tropical cyclone behavior. The growing population density since the 1950s has augmented the potential for disaster.

Simulated changes to tropical cyclones across the Paleocene-Eocene Thermal Maximum (PETM) boundary

Tropical cyclones are an important meteorological and climatological process in Earth's climate system. These intense, localized storms mainly form over warm equatorial oceans, and propagate poleward. During their lifetime, tropical cyclones can strengthen leading to intense winds and rainfall events. These storms also carry moist energy that contribute to the poleward transport of atmospheric energy. Presently, concern exists about how the characteristics of tropical cyclones will change in a future warming world. The Paleocene Eocene Thermal Maximum (PETM) was a time in Earth's deep past in which the planet warmed by 5° - 8 °C due to an increase in atmospheric CO2. It is thus of interest to understand how past warming affected tropical cyclone behavior. Here, a high resolution (25 km) atmospheric model is used to study changes in tropical cyclones across the PETM boundary. Orbital variation is also investigated as an additional forcing mechanism at the time of the PETM. The climate simulations indicate that greenhouse forcing leads to a poleward shift in TCs, much like projected future scenarios and in simulations of other warm periods in Earth history. It is also found that the orbital forcing response is very different than the greenhouse cases due to the difference in thermal response, which, in turn, induces a different dynamical response in wind shear. Although the spatial pattern between changes across the PETM and the future differ, there are still many similarities in TC response for these two very different periods in time, indicating the robustness of the TC response to greenhouse warming.

Detecting tropical cyclones from climate- and oscillation-free tree-ring width chronology of longleaf pine in south-central Georgia

The knowledge of past tropical cyclone (TC) activity is vital to understanding patterns of current and future TCs and how they will impact society, infrastructure, and the natural system. Various historical, biological, and geological proxies are commonly used to reconstruct TC behavior; however, these records vary significantly in their temporal resolution. Tree rings are known to provide high-resolution data and have been proven as a valuable proxy record of past TC activity. Here we aim to produce a TC reconstruction based on tree-ring width data of longleaf pine (Pinus palustris Mill.) located in Lake Louise near Valdosta, Georgia. Results of growth-climate analysis showed that all climate and oscillation variables influence the tree growth, and removing this climate influence may be necessary to unmask the TC signal. For this purpose, we used stepwise linear regression to iteratively model tree growth with monthly climate factors (precipitation, temperature, drought) and monthly oscillation indices (ENSO, AMO, NAO, PDO) to obtain residual chronologies. Tree-ring chronologies were compared to TC data from the National Hurricane Center's North Atlantic Hurricane Database (HURDAT2) for a 150-km buffer zone around Lake Louise between 1894 and 1999. Of the storms that entered the buffer, 13 of the 17 ≤−0.3 growth rings and 8 of the 10 ≤−0.4 growth rings occurred in the year directly after a TC event. Our results revealed the strong climate and oscillation influence in the raw chronology and no significant TC signal. However, the removal of temperature and precipitation influence from raw chronology unmasked the TC signal (p < 0.05). The TC signal was even more pronounced if influence of oscillation indices on growth had been also removed. The most pronounced TC signal was identified between most intense TCs (≥ 33 ms−1) and the climate and oscillation signal-free chronology. We emphasize that future research is needed for validation and elimination of the influence of other external growth drivers, as well as replication studies at multiple sites using similar statistical applications.

A statistical–parametric model of tropical cyclones for hazard assessment

Abstract. We present the formulation of an open-source, statistical–parametric model of tropical cyclones (TCs) for use in hazard and risk assessment applications. The model derives statistical relations for TC behaviour (genesis rate and location, intensity, speed and direction of translation) from best-track datasets, then uses these relations to create a synthetic catalogue based on stochastic sampling, representing many thousands of years of activity. A parametric wind field, based on radial profiles and boundary layer models, is applied to each event in the catalogue that is then used to fit extreme-value distributions for evaluation of return period wind speeds. We demonstrate the capability of the model to replicate observed behaviour of TCs, including coastal landfall rates which are of significant importance for risk assessments.

Increased typhoon activity in the Pacific deep tropics driven by Little Ice Age circulation changes

The instrumental record reveals that tropical cyclone activity is sensitive to oceanic and atmospheric variability on inter-annual and decadal scales. However, our understanding of the influence of climate on tropical cyclone behaviour is restricted by the short historical record and the sparseness of prehistorical reconstructions, particularly in the western North Pacific, where coastal communities suffer loss of life and livelihood from typhoons annually. Here, to explore past regional typhoon dynamics, we reconstruct three millennia of deep tropical North Pacific cyclogenesis. Combined with existing records, our reconstruction demonstrates that low-baseline typhoon activity prior to 1350 ce was followed by an interval of frequent storms during the Little Ice Age. This pattern, concurrent with hydroclimate proxy variability, suggests a centennial-scale link between Pacific hydroclimate and tropical cyclone climatology. An ensemble of global climate models demonstrates a migration of the Pacific Walker circulation and variability in two Pacific climate modes during the Little Ice Age, which probably contributed to enhanced tropical cyclone activity in the tropical western North Pacific. In the next century, projected changes to the Pacific Walker circulation and expansion of the tropics will invert these Little Ice Age hydroclimate trends, potentially reducing typhoon activity in the deep tropical Pacific.

Impact of Rapid‐Scan‐Based Dynamical Information From GOES‐16 on HWRF Hurricane Forecasts

AbstractObservations of dynamical information in the upper levels of tropical cyclones at high spatiotemporal resolutions are rare but very important to the analysis and prediction of the storm evolution and landfall impacts. These observations are now becoming routinely available from the new generation of geostationary weather satellites. Understanding and optimizing the utilization of that information in numerical weather prediction models is a vital step toward simulating tropical cyclone behavior and improving forecasts. The Advanced Baseline Imager (ABI) onboard GOES‐16 is providing high spatial and temporal resolution images that can be targeted on North Atlantic tropical cyclones. In addition to a full‐disk scan every 10 min and a CONUS scan every 5 min, the ABI also has a flexible “mesoscale scan” mode featuring limited moving domains at 1‐min intervals. The mesosector can focus on a targeted storm center with a 10°×10° domain coverage that follows the storm movement. Using this 1‐min ABI imagery to track cloud motions, automated algorithms have been developed to produce enhanced, high‐resolution atmospheric motion vectors (AMVs) during a targeted tropical cyclone event. These high spatiotemporal AMVs represent estimates of the wind field around the storm and can provide critical dynamical information on the targeted storm and its near environment. This information can help improve the representation of the initialized vortex in numerical model analyses. To study the impact of the enhanced AMV observations on numerical weather prediction, the Hurricane Weather Research Forecast (HWRF) model is used in a series of assimilation and forecast experiments. Three destructive Atlantic hurricane cases from 2017, Harvey, Irma, and Maria, are chosen as case studies. The results show that the assimilation of the enhanced AMVs from GOES‐16 consistently improves the HWRF hurricane track and size forecasts, and have mixed impacts on intensity forecasts. These results augment previously published studies on optimizing the quantitative use of new generation geostationary satellite rapid‐scan observations for improving high impact weather forecasts.

Seasonal forecasting of tropical cyclones in the North Indian Ocean region: the role of El Niño-Southern Oscillation

In this study, we have investigated the contribution of El Nino-Southern Oscillation (ENSO) to the North Indian Ocean (NIO) tropical cyclone (TC) activity and seasonal predictability. A statistical seasonal prediction model was developed for the NIO region tropical cyclone genesis, trajectories and landfalls using the Southern Oscillation index (SOI: as a metric of ENSO) as a predictor. The forecast model utilised kernel density estimation (KDE), a generalised additive model (GAM), Euler integration, and a country mask. TCs from the Joint Typhoon Warning Centre were analysed over the 35-year period from 1979 to 2013. KDE was used to model the distribution of cyclone genesis points and the cyclone tracks were estimated using the GAM, with velocities fit as smooth functions of location according to ENSO phase and TC season. The best predictor lead time scales for TC forecast potential were assessed from 1 to 6 months. We found that the SOI (as a proxy for ENSO) is a good predictor of TC behaviour 2-months in advance (70% skill). Two hindcast validation methods were applied to assess the reliability of the model. The model was found to be skillful in hindcasting NIO region TC activity for the pre and post monsoon season. The distribution of TC genesis, movement and landfall probabilities over the study period, as well as the hindcast probabilities of TC landfall during ENSO events, matched well against observations over most of the study domain. Overall, we found that the phase of ENSO has the potential to improve NIO region TC seasonal forecast skill by about 15% over climatological persistence.

Critical behavior of tropical cyclones

Critical phenomena have previously been reported in rainfall patterns over the tropical oceans. Confirming and extending that discovery, we identify a critical temperature Tc, and a linear T-Tc power law dependence, typical of a continuous phase transition, in existing data and excellent fits for the power dissipation index (PDI) for Northern Hemisphere hurricanes vs sea surface temperature T. It is suggested that tropical cyclone formation can usefully be regarded as a phase transition of the warm ocean-atmosphere system, driven by disequilibrium in atmospheric water content. The related implication of this previously unrecognized, rapid temperature dependence of tropical cyclone strength is noted.

Consequences of regularizing the Sawyer–Eliassen equation in balance models for tropical cyclone behaviour

AbstractThe consequences of regularizing the Sawyer–Eliassen equation to calculate the stream function for the axisymmetric secondary circulation of a tropical cyclone are explored. Regularization is an ad hoc procedure in which the coefficients of the equation are suitably modified to replace negative values of the discriminant by small positive values, thereby ensuring that the equation is globally elliptic. The consequences of the procedure may be understood in terms of the analogue behaviour of a stretched membrane subject to a particular force distribution. Several regularization procedures are assessed by comparing the azimuthally averaged radial flow from a three‐dimensional numerical simulation of a tropical cyclone with that from an axisymmetric balance calculation of the Sawyer–Eliassen equation, forced by diabatic and frictional terms diagnosed from the simulation. The comparison shows that the largest challenge for regularization occurs in regions of inertial instability, especially when the diagnosed forcing overlaps with such regions. In the example shown, the diagnosed balanced flow is sensitive to the particular regularization procedure and none of the procedures examined give a flow that is structurally and quantitatively close to that obtained from the numerical solution in and near the region of regularization. The flow in regions of large vertical shear that are common in the lower part of the boundary layer is less sensitive to the regularization procedure, even though such regions are ones in which there is (frictional) forcing. Nevertheless, there are comparatively large differences between the low‐level inflow in the azimuthally averaged numerical solution and the axisymmetric balance solution. These differences can be attributed to the intrinsic lack of balance in the boundary layer. This finding, together with the issues associated with regularization, is further confirmation that balance dynamics is unable to adequately capture the flow in the boundary layer, contrary to recent claims.

Orbitally Induced Variation of Tropical Cyclone Genesis Potential Over the Western North Pacific During the Mid‐Piacenzian Warm Period: A Modeling Perspective

AbstractThe mid‐Piacenzian (3.264 to 3.025 Ma) is the most recent warmer‐than‐present interval in the geological past, with clear orbital‐scale variability in climate and environments. However, it remains unclear how the orbitally induced climate change may regulate the behavior of tropical cyclones (TCs). Here we use a fully coupled climate model to examine the response of TC genesis potential to different orbital configurations specific to the mid‐Piacenzian time slab. Under the Pliocene Research, Interpretation, and Synoptic Mapping version 3 boundary conditions that use modern orbital configurations, our results show that environmental conditions in the mid‐Piacenzian are less favorable for storm formation over the western North Pacific than the preindustrial. By performing a suite of sensitivity experiments, we find that orbital configurations significantly influence the magnitude and phase of genesis potential via the modification of the atmospheric thermal structure and associated large‐scale circulations. Regarding the overall favorability, increased and decreased orbitally induced insolation leads to less and more favorable conditions for storm formation over the western North Pacific, respectively. Under several extreme orbital parameters (e.g., when northern hemisphere summer insolation is at a minimum), there is an increasing favorability for genesis in the mid‐Piacenzian relative to the preindustrial. This is attributed to the fact that the orbitally induced increase in TC genesis exceeds the reduction from the Pliocene Research, Interpretation, and Synoptic Mapping version 3 boundary conditions. Our results highlight potential orbital‐scale variability in TC activity during the mid‐Piacenzian, implying possible changes in TC‐induced vertical mixing, which might play a potential role in regulating the orbital‐scale variation of tropical/global climate during the Pliocene.

Quantification and Exploration of Diurnal Oscillations in Tropical Cyclones

AbstractDiurnal oscillations of infrared cloud-top brightness temperatures (Tbs) in tropical cyclones (TCs) as inferred from storm-centered, direction-relative longwave infrared (~11 μm) imagery are quantified for Northern Hemisphere TCs (2005–15) using statistical methods. These methods show that 45%, 54%, and 61% of at least tropical storm-, hurricane-, and major hurricane-strength TC cases have moderate or strong diurnal signals. Principal component analysis–based average behavior of all TCs with intensities of 34 kt (17.5 m s−1) or greater is shown to have a nearly symmetric diurnal signal where Tbs oscillate from warm to cold and cold to warm within and outside of a radius of approximately 220 km, with maximum central cooling occurring in the early morning (0300–0800 local standard time), and a nearly simultaneous maximum warming occurring near the 500-km radius—a radial standing wave with a node near 220-km radius. Amplitude and phase of these diurnal oscillations are quantified for individual 24-h periods (or cases) relative to the mean oscillation. Details of the diurnal behavior of TCs are used to examine preferred storm and environmental characteristics using a combination of spatial, composite, and regression analyses. Results suggest that diurnal, cloud-top Tb oscillations in TCs are strongest and most regular when storm characteristics (e.g., intensity and motion) and environmental conditions (e.g., vertical wind shear and low-level temperature advection) support azimuthally symmetric storm structures and when surrounding mid- and upper-level relative humidity values are greater. Finally, it is hypothesized that larger mid- and upper-level relative humidity values are necessary ingredients for robust, large-amplitude, and regular diurnal oscillations of Tbs in TCs.

Variability of upper‐ocean characteristics and tropical cyclones in the South West Indian Ocean

AbstractTrack and intensity are key aspects of tropical cyclone behavior. Intensity may be impacted by the upper‐ocean heat content relevant for TC intensification (known as Tdy) and barrier layer thickness (BLT). Here the variability of Tdy and BLT in the South West Indian Ocean and their relationships with tropical cyclones are investigated. It is shown that rapid cyclone intensification is influenced by large Tdy values, thick barrier layers and the presence of anticyclonic eddies. For TC generation in the South West Indian Ocean, the parameter Tdy was found to be important. Large BLT values overlay with large Tdy values during summer. Both fields are modulated by the westward propagation of Rossby waves, which are often associated with ENSO. For example, the 1997–1998 El Niño shows a strong signal in Tdy, SST, and BLT over the South West Indian Ocean. After this event, an increasing trend in Tdy occurred over most of the basin which may be associated with changes in atmospheric circulation. Increasing SST, Power Dissipation Index and frequency of Category 5 tropical cyclones also occurred from 1980 to 2010. To further examine the links between tropical cyclones, Tdy, and BLT, the ocean response to Category 5 Tropical Cyclone Bansi that developed near Madagascar during January 2015 was analyzed. Its unusual track was found to be linked with the strengthening of the monsoonal north westerlies while its rapid intensification from Category 2 to Category 4 was linked to a high‐Tdy region, associated with a warm core eddy and large BLT.

Insight into tropical cyclone behaviour through examining maritime disasters over the past 1000 years based on the dynastic histories of China – A dedication to Ocean Researcher V

This paper uses China's historical records to gather information on maritime disasters caused by tropical cyclones. Official records show that there were a total of thirteen major maritime disasters possibly caused by tropical cyclones. Maritime disaster variation trends indicate that tropical cyclones tend to strike the southern coast of China during a La Niña-like stage whereas an El Niño-like stage leads to tropical cyclones being guided northward toward the Korean Peninsula and Japan. During China's Yuan Dynasty (AD 1271–1368) Kublai Khan tried to invade Japan twice during an El Niño-like stage and encountered intense tropical cyclones, which the Japanese called Kamikaze. During a La Niña-like stage, multiple maritime disasters occurred in the East China Sea, the Taiwan Strait and the South China Sea in the Qing Dynasty (AD 1636–1912). Indeed, the historical record of the Qing Dynasty details maritime disasters at least 9 times. These events were also caused by tropical cyclones. In addition, statistics on the seasons of tropical cyclone genesis and their landfall locations from AD 1945–2013 in the Northwest Pacific Ocean region reveal that in summer, tropical cyclones tend to make landfall along coastal regions north of Fujian Province, eastern China; however, in autumn and winter, cyclones tend to be guided further southward to make landfall in southern China (Hainan), Vietnam, and the Philippines. This phenomenon in seasonal variation is reflected in the maritime disaster events recorded for coastal regions of southeastern China and landfall locations of tropical cyclones during the Qing Dynasty.