Preface

Since the start of the 21st century, changes in the current and future climate have been of greatest concern in the atmospheric and climate science communities. This includes changes in the frequency and strength of dangerous phenomena such as tropical cyclones. Although much research has been dedicated to this topic, there continues to be investigations into the dynamics of tropical cyclones including the dynamics that govern their movement. Remote sensing techniques and numerical models continue to be key tools in these investigations. In spite of all the advances in tropical storm research, these events continue to behave in ways that surprise us as the last few years have demonstrated.

While there will always be those events that develop rapidly, some storms have developed and then, sometimes unexpectedly, stalled over areas for a few days due to the lack of strong forces to steer them. This has led to some cities or regions being exposed to days of record setting rains or being lashed by strong winds for 24 to 48 hours. Heavy rain and flooding continue to be the most economically damaging and disruptive features associated with land falling tropical cyclones. There is research suggesting that in a warmer world, tropical cyclones will produce more precipitation since warmer air will support larger amounts of water vapor.

Therefore it is important to compile and publish the latest research every so often on recent developments in the area of tropical cyclone studies. This book includes several contributions of importance. This work will highlight tropical cyclone activity across the globe over the last decade and put this activity in the context of the previous 30 years. For the first time, all the major ocean basins have four relatively complete decades of tropical cyclone frequencies and good estimates of intensity. This work will show that the activity of the most recent decade is mostly similar to the decade before. Globally, the number of tropical cyclones has increased over the last four decades, but these increases are not statistically significant. Additionally, the increases were uneven across each ocean basin, and some such as the south Pacific have shown decreases.

In atmospheric science, there are several observational and model datasets that can be used in the study of tropical cyclones. The observational datasets are augmented by remotely sensed data. This work examines a couple of the most commonly used datasets and examines the precipitation and hydrology as well as the atmospheric dynamics. One study (Liu et al.) will demonstrate, using case studies, that different results will be obtained using datasets that may assimilate information from different platforms. For example, some of these datasets can produce a wet bias in their results. This study describes three main datasets and gives details with respect to data access, documentation, and user services as well. Another study (Guimarães) evaluates models that are part of the Coupled Model Intercomparison Project Phase 6 (CMIP6) and using the quantity Accumulated Cyclone Energy (ACE) with respect to recent climate and what the results mean to the future. This study compared model performance to the current observations, and then examined the future. There was no obvious trend for future scenarios of ACE, and no clear majority of increases or decreases of this quantity by different modeling groups.

While many studies examine the synoptic and dynamic features associated with the growth of tropical cyclones or their landfall, relatively few (Fedorova et al.) examine several case studies of weaker storms near the equator that give rise to fog and mist events over Northeast Brazil. These events can have serious consequences for aerospace operations. In these cases, it was found that the tropical cyclones or disturbances do not come ashore directly, but it is the indirect influence caused by secondary circulations that lead to the formation of fog and mist events. Also, tropical cyclones such as tropical storms and hurricanes generally emerge from tropical disturbances. Over the Atlantic region these disturbances occur with some regularity emanating from formation regions over Africa (African Easterly Waves – AEWs). Reyes and Shen use this quasi-periodicity to develop algorithms to forecast their occurrence using recurrence theory. These results show some promise in extending the lead time for the forecasting of the tropical cyclone "seeds".

Other parts of the world, such as the countries of the Northwest Pacific, are also vulnerable to the occurrence of tropical cyclones. A review by Wu and Conde summarizes the previous research done by the authors and collaborators involving the response of coastal ocean dynamics to tropical cyclone occurrence for variables such as sea surface temperature, sea surface salinity, storm surge simulation, and extreme rainfall. They also propose three research paths for future work that involves observational, dynamic, and model studies in order to improve the understanding of the future threat these regions may face due to tropical cyclones.

Satellite techniques are often used to determine the intensity of tropical cyclones using the area of cold cloud tops near the center as well as storm feature shapes as determined using visible or infrared imagery (the Dvorak technique). The work of Yurchak proposes using the character of the spiral rainbands as derived from not only satellite techniques, but augmenting this with ground and aircraft-based RADAR to determine the shape of the spiral bands. This information can be used to develop a hyperbolic-logarithmic streamline equation that ultimately relates the model to maximum wind speed.

Lastly, it was a pleasure to edit this book and work with all the authors and the staff of IntechOpen. The process was rather smooth. I am grateful to all the authors for their contributions, and the staff at IntechOpen for their hard work in keeping the process moving along. This is the third such project that I've been involved with and the experience has been good each time. Finally, it is my hope that the tropical meteorology community finds this book to be a useful resource for augmenting their own studies as well as providing a basis for future research.

> **Anthony R. Lupo** Atmospheric Sciences Program, School of Natural Resources, 302 Anheuser Busch Natural Resources Building, University of Missouri, Columbia, MO, USA

Section 1

Climatological Behavior

Section 1
