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Financiado para publicación en acceso aberto: Universidade de Vigo/CISUG In this study was performed a comparative climatology of outer tropical cyclone (TCs) size using radial wind profiles. A wind speed of 2 ms (4 kt) was taken as the threshold to define the TC size. The method proposed by Willoughby et al. (2006) (W06) to determine the wind profile showed the least variance and the smallest coefficient of variation of all profiles. W06 correctly described the radial wind structure of storms such as Hurricane Irma (2017) and Cyclone Giri (2010), compared with the European Centre for Medium-Range Weather Forecasts ERA-5 reanalysis data. Thus, W06 was used to develop the climatological TC size (TCSize) database. It was found that the tropical cyclones are largest when the maximum wind speed ranges between 20 and 40 ms and they most frequently reach a size between 700 and 800 km. The TCs exhibit their maximum size when they are in extratropical latitudes, while the smallest are observed in the low latitudes of both hemispheres. The global mean size is 748.7 km with a 95% confidence interval of [748.2,749.2] km. Median storm size is largest in the North Atlantic basin and smallest in the North Indian Ocean. The method proposed here is designed to be an objective metric that can be quickly applied to any TC when its position, maximum wind speed, and minimum central pressure are known. As a result, a TCSize database was created for all ocean basins, which could be useful for many applications, including different risk analyses. Xunta de Galicia | Ref. ED481A-2020/193 Xunta de Galicia | Ref. ED481B 2019/070 Xunta de Galicia | Ref. ED431C 2021/44

Under a changing climate, projections estimate that over the next thirty years, extreme Tropical Cyclones (TCs) will increase in frequency, with two to three times more Category 4 and 5 hurricanes in the Atlantic basin between 20°N and 40°N. In recent years, the Caribbean Sea and Atlantic Ocean basins have experienced several extreme TCs, resulting in extensive human, ecological, and economic damage [1], [2], [3]. To improve understanding of TCs and their potential impacts in the face of climate change, physically based understanding of past climate and modern TC dynamics is necessary. Despite the well-known Atlantic hurricane season, surface observations of the isotopic evolution of TC's moisture and the propagation of isotopically distinct pulses across surface and subsurface water reservoirs are lacking. In this data article, we provide novel high frequency sampling of surface rainfall isotope compositions (δ18O, δ2H, and d-excess in ‰) for Hurricanes Otto (Costa Rica, 2016), Nate (Costa Rica, 2017), Irma (Cuba and The Bahamas, 2017), Maria (Cuba and The Bahamas, 2017), and Dorian (The Bahamas, 2019). These five TCs were characterized by unprecedented impacts during continental and maritime landfalls and passages. In total, 161 surface rainfall samples were collected in passive devices [4] with event-based and daily frequencies, resulting in the first surface isotopic tempestology anatomy across the Caribbean Sea and Atlantic Ocean basins to date. Derived rainfall from TCs often results in large input amounts of isotopically distinct water over an area from few hours to several days, and therefore this unique isotope composition is propagated through surface and shallow subsurface reservoirs. Our data also include spring (N=338) and surface water (N=334) isotope compositions following the impact of Hurricane Otto and Tropical Storm Nate in central Costa Rica. As this region is well-known for its diverse rainfall dynamics and as a climate change ‘hot spot’ [5], [6], [7], our data provide an opportunity to improve and complement modern and past climate interpretations often derived from satellite products and calcite-δ18O paleoclimatic archives in light of climatic forcing, TC rainfall amounts and recharge rates, and the hypothesized climatic-induced decline of past Mesoamerican civilizations. Bajo un clima cambiante, las proyecciones estiman que durante los próximos treinta años, los ciclones tropicales extremos (CT) aumentarán en frecuencia, con dos o tres veces más huracanes de categoría 4 y 5 en la cuenca atlántica entre 20 ° N y 40 ° N. En los últimos años, las cuencas del Mar Caribe y el Océano Atlántico han experimentado varias CT extremas, lo que ha provocado grandes daños humanos, ecológicos y económicos [1], [2], [3]. Para mejorar la comprensión de las CT y sus impactos potenciales frente al cambio climático, es necesaria una comprensión física del clima pasado y de la dinámica de las CT modernas. A pesar de la conocida temporada de huracanes en el Atlántico, faltan observaciones superficiales de la evolución isotópica de la humedad de TC y la propagación de pulsos isotópicamente distintos a través de depósitos de agua superficiales y subterráneos. En este artículo de datos, proporcionamos un muestreo novedoso de alta frecuencia de la composición de isótopos de lluvia superficial (δ18O, δ2H y exceso d en ‰) para los huracanes Otto (Costa Rica, 2016), Nate (Costa Rica, 2017), Irma (Cuba y Las Bahamas, 2017), María (Cuba y Las Bahamas, 2017) y Dorian (Las Bahamas, 2019). Estas cinco operaciones de cooperación técnica se caracterizaron por impactos sin precedentes durante los pasajes y recaladas continentales y marítimas. En total, se recolectaron 161 muestras de lluvia superficial en dispositivos pasivos [4] con frecuencias diarias y basadas en eventos, lo que resultó en la primera anatomía de tempestología isotópica superficial en las cuencas del Mar Caribe y el Océano Atlántico hasta la fecha. La lluvia derivada de los CT a menudo da como resultado grandes cantidades de entrada de agua isotópicamente distinta en un área desde unas pocas horas hasta varios días y, por lo tanto, esta composición isotópica única se propaga a través de depósitos superficiales y subterráneos poco profundos. Nuestros datos también incluyen composiciones isotópicas de manantiales (N = 338) y aguas superficiales (N = 334) luego del impacto del huracán Otto y la tormenta tropical Nate en el centro de Costa Rica. Como esta región es bien conocida por su diversa dinámica de lluvias y como un 'punto caliente' del cambio climático [5], [6], [7], nuestros datos brindan una oportunidad para mejorar y complementar las interpretaciones climáticas modernas y pasadas a menudo derivadas de productos satelitales y archivos paleoclimáticos de calcita-δ18O a la luz del forzamiento climático, las cantidades de lluvia de CT y las tasas de recarga, y el supuesto declive inducido por el clima de las civilizaciones mesoamericanas pasadas. Universidad Nacional, Costa Rica Escuela de Química

The North Atlantic tropical cyclones (TCs) are iconic weather extremes of the SEUS. Although TCs are weather events, their periodic seasonal occurrence in the North Atlantic Basin and their landfalls along the SEUS coastline has derived significant interest on their low frequency variability. A rich body of theoretical, observational, and empirical work to understand the morphology and intensity features of TC has also been discussed in this chapter including metrics to measure their intensity and seasonal activity.

Tropical systems are major natural forces that impact regions physically, hydrologically, and ecologically. Tropical systems are initiated by warm ocean temperatures, evaporation, condensation, and energy release, and associated pressure differential and wind flow. Tropical waves, tropical depressions, and tropical storms are sources of rainfall that could be beneficial when wind speed is lower not to cause severe damage. Tropical systems of higher wind speeds are categorized by wind speed and are referred to as hurricanes in the Atlantic, Gulf of Mexico, and Eastern Pacific, cyclones in Indian Ocean, and typhoons in Western Pacific. These systems, when make landfall or pass too close to land, have destructive forces causing damages to infrastructure, beaches, landscape, vegetation, life, and property. The sources of damage are high wind speed, high intensity, and magnitude of rainfall and storm surge. Flooding, landslide, infrastructure failures like levee failures are common. This chapter presents mainly Atlantic hurricanes with specific details of known hurricane events and their interaction and impact on landfall on the US mainland with a case study of South Florida. The relationship of El Nino Southern Oscillation (ENSO) phenomenon and Atlantic tropical system development is presented. Since 1851, out of 15 years of high number of storms, and out of 15 high number of hurricane years, 11 were during La Nina and Neutral ENSO years, and only four during El Nino years. Out of eight high number of major hurricane years, only one was during an El Nino year showing that El Nino years have fewer storms than La Nina and neutral years. Positive aspects of tropical systems in breaking severe droughts are also presented.

It is estimated that the 2017 Atlantic hurricane season caused a substantial $203 billion in damages. Changes in hurricane intensity or/and frequency may be expected due to the changing climate. This chapter presents a risk and cost-benefit based framework to assess the potential hurricane damage risks to residential construction and investigate the cost-effectiveness of different adaptation strategies under various wind speed change scenarios due to climate change. Various adaptation strategies are developed in an attempt to mitigate damage costs. Three case study locations (Miami-Dade County, New Hanover County, and Galveston County) are presented. The damage risk estimated by the framework is validated by comparing with the HAZUS-MH Hurricane Model and the Florida Public Hurricane Loss Model. This study finds that climate change may have a substantial impact on damage estimation in coastal areas, and that certain adaptation strategies can cost-effectively decrease the damage costs.

The complexity of the climate system entails, among many other implications, that the evolution of surface climate is not monotonic. This is true for both the present and the future evolution of climate, particularly on the regional scale. Trends in temperature or precipitation can be amplified, or partially offset, at the regional scale, as a consequence of changes in the amplitude or spatial configuration of major patterns of atmospheric circulation. Results published in the latest Intergovernmental Panel on Climate Change (IPCC) report have stressed several important changes to the location or extent of important mid-latitude features such as: the Azores high and the Icelandic low that were both smaller in extent during the 1960s and 1970s, and increased in the 1980s and 1990s; and the eastward shift of the Aleutian low from the 1970s to the 2000s. Some of the most important large-scale atmospheric circulation patterns, including the North Atlantic Oscillation (NAO), Pacific North American (PNA) and El Nino Southern Oscillation (ENSO) are characterized by large values of interannual and decadal variability, and changes in their spatial configuration. For example, the classical pattern of ENSO with a warming centre located along the eastern Pacific and spreading north and south close to the American coast has been less frequent and changing toward a different configuration with the warming centre located further in the central Pacific. Tropical cyclones, including Atlantic hurricanes and Pacific typhoons, show a significant evolution over the last 30 years with recent analysis showing a poleward migration of tropical cyclones in both hemispheres of about one degree of latitude per decade.

Hurricanes, typhoons, and tropical cyclones are severe tropical storms. Although these storms share common characteristics in formation and impact, the term used is determined by wind speed and location. These storms form over warm water and draw energy from the evaporation of water as they pass over the ocean surface. The storms begin simply as an area of low pressure and thunderstorms called a tropical disturbance. As the warm air causes water to evaporate, it creates lift in the low pressure area. The rising warm, moist air releases energy as it cools and condenses into rain clouds. The process continues building energy in the rainclouds which can erupt into a violent storm encompassing hundreds of square miles. As the winds begin to rotate over the warm water, energy continues to build, eventually creating a hurricane, typhoon, or tropical cyclone. Throughout this chapter, the term “hurricane” will be used.

Highlights: • North Atlantic sea surface temperature exhibits high decadal predictability potential. • Model bias hinders exploiting the decadal predictability potential. • An innovative method was developed to overcome some of the bias problem. • North Atlantic sea surface temperature will stay anomalously warm until about 2030. Abstract: The Atlantic Meridional Overturning Circulation (AMOC), a major current system in the Atlantic Ocean, is thought to be an important driver of climate variability, both regionally and globally and on a large range of time scales from decadal to centennial and even longer. Measurements to monitor the AMOC strength have only started in 2004, which is too short to investigate its link to long-term climate variability. Here the surface heat flux-driven part of the AMOC during 1900–2010 is reconstructed from the history of the North Atlantic Oscillation, the most energetic mode of internal atmospheric variability in the Atlantic sector. The decadal variations of the AMOC obtained in that way are shown to precede the observed decadal variations in basin-wide North Atlantic sea surface temperature (SST), known as the Atlantic Multidecadal Oscillation (AMO) which strongly impacts societally important quantities such as Atlantic hurricane activity and Sahel rainfall. The future evolution of the AMO is forecast using the AMOC reconstructed up to 2010. The present warm phase of the AMO is predicted to continue until the end of the next decade, but with a negative tendency.

An inherent feature of the climate is its strong variability on a vast range of timescales, from seasonal to multimillennial and beyond. Decadal variability, which is the topic of this chapter, has large implications for society, as its consequences can be experienced by individuals during their own lifetime. Examples of decadal variability include the Dust Bowl drought of the 1930s in the American and Canadian prairie lands, the Sahel drought of the 1970s and 1980s, the ongoing drought which started in 2000 in the southwestern United States, and the multidecadal variability in Atlantic hurricane activity during the twentieth century. Furthermore, it is the decadal to multidecadal variability that makes the detection of anthropogenic climate change a challenge, since global warming evolves on a similar timescale. The detection problem specifically applies to the regional scale, where natural variability is the strongest. It is a central challenge of climate science to understand and possibly predict such regional-scale climate variability and change over timescales of decades.

One of the most powerful tools of signal theory is the so-called wavelet-coherence transform spectral analysis . Using this tool we determine the most prominent signals between North Atlantic hurricanes of all categories, as well as involved terrestrial phenomena: SST, AMO, AD (African dust), and geoexternal phenomena such as solar activity (SS), geomagnetic activities (K p ), and GCR (galactic cosmic rays). Results indicate that among the most prominent common signals for hurricanes, SST, AMO, and GCR are those of period of 30 ± 2 years. The high level of coherence between GCR and hurricanes indicates a stronger modulation effect by GCR, probably on the basis of the mechanisms described by Ram et al. (2009). For the case of SS, the most intense signals remain at the 11 and 22 years frequencies. For AD, the time interval data is relatively short (since 1966), nevertheless, several well-defined signals are found with hurricanes of different categories in the range 0.25 to 13 years. A clear anti-correlation is found between Categories 5, 4, and 3 hurricanes with AD. While the most prominent periodicity for hurricanes of Category 4 or less is 1 year, for Category 5 hurricanes there are well-defined periodicities at 8 and 10 years. These allow for forecasting of Category 5 hurricanes. In preliminary form we can argue that the next one will occur 2014. Also, it is determined for the first time, that hurricanes of Category 4 are able to evolve, or not, into Category 5 depending on whether or not their trajectory crosses the geographic areas of deep waters (10 °W–20 °W latitude).

Microseisms seen on seismograms worldwide were once viewed as “noise” contaminating records of earthquakes. However, these low-amplitude oscillations generated by storms over the oceans are now recognized as carriers of an important meteorological “signal”. Decades-long archives of analog seismograms may thus represent a high-resolution record of climate change significantly longer than those based on traditional meteorological observations. One of the first phenomena investigated by the then-new field of seismology, microseism research began with their identification around 1870. Improved characterization came from subsequent investigations in Europe, Japan, and North America, which sought out their sources and source regions. Two-generation mechanisms were identified in the mid-twentieth century. In both, microseisms originate with atmospheric energy in the form of storms over the oceans. It is coupled into the water column via the generation of ocean swell, transmitted to the seafloor, and then travels as elastic waves at the seafloor. Analysis of secondary microseisms, recorded in eastern North America during August 1992 Saffir/Simpson category 5 hurricane Andrew, shows the feasibility of using these signals to identify North Atlantic Ocean hurricanes. The shift in dominant microseism frequency with Andrew intensification demonstrates that these microseisms were generated over the deep waters of the North Atlantic Ocean at or near the hurricane and are thus a near real-time record of hurricane changes. Variations in secondary microseism frequency and amplitude allow detection of the hurricane while over the ocean and up to ∼2000 km from the recording station. Analog seismograms from seismic stations in North America may thus document unobserved North Atlantic hurricanes. However, uncertainties remain. The relative contributions of deep- and shallow-water sources remain uncertain, and the generation of microseisms with transverse wave components lacks a satisfactory explanation. Better understanding of the various controls on microseism properties is necessary before information in these waveforms can be used to infer storm characteristics, especially for less-energetic storms.

The twentieth century has featured considerable global warming of the order of 0.7°C. The Earth will continue to warm over the next several decades under any plausible scenario, but the climate trajectory will not follow a steady path, due to the presence of natural variability. Global warming will inevitably be accompanied by regional-scale natural variability and change, which can have profoundly important impacts. Examples during the twentieth century include the Dust Bowl drought in the USA of the 1930s, the Sahel drought of the 1970s and 1980s, the ongoing drought in the southwestern US, and the decadal-scale changes in Atlantic hurricane activity. It is a central challenge of climate research to understand the dynamics of these fluctuations and predict such regional-scale climate variability and change over timescales of decades or even longer. The origin and future of decadal to centennial variability is the topic of this chapter.

Publisher Summary It is not possible to directly measure the strength of the thermohaline circulation (THC). But its strength can be inferred from proxy measurements of the North Atlantic SST and salinity anomalies (which are directly related to each other) minus the sea level pressure anomaly (SLPA) over the broad Atlantic (0–50°N; 70°W–10°W). When the THC is strong, the Atlantic atmospheric and oceanic subtropical gyres are weaker than normal. When the Atlantic THC is weaker than average, the gyres are stronger than normal. With regards to multidecadal variations of Atlantic major hurricane activity, it is possible to give a sequence of physical arguments for how a year or a multidecadal period with a stronger than normal THC will have tropical Atlantic conditions associated, which are more favorable for Atlantic basin major hurricane activity. Among these conditions are positive tropical Atlantic sea surface temperature anomaly, lower tropical Atlantic SLPAs, weaker trade winds, and smaller values of tropospheric vertical wind shear. There is no evidence that Atlantic hurricane activity is significantly impacted by CO2 increases or by global mean surface temperature changes. This myth should be put to rest. It is the natural variability of the Atlantic's meteorological parameters that one must be concerned about.

The fate of water masses in the Equatorial Undercurrent (EUC) in the Atlantic is studied using a high-resolution ocean model. Lagrangian trajectory analysis is used to determine sites where water masses from the EUC upwell and later downwell. The use of Lagrangian mean transports to trace particles takes into account high-temporal variability in the tropics. Most EUC water upwells in the equatorial region. The pathways between the EUC core and the upwelling sites indicate that most particles upwell rather directly at the equator. Other upwelling sites are found close to the African contintent and along the Gulf Stream. After upwelling, particles subduct again in the tropical and subtropical Atlantic. The particles that recirculate back to the EUC experience, on average, five upwellings and downwellings. The sites where the particles subduct for the last time before returning to the EUC are found mainly along the South Equatorial Current. Most particles follow the western boundary back to the tropics. Two thirds of EUC transport at 20°W does not recirculate, but leaves the Atlantic basin at the southwestern side to participate in the global meridional overturning circulation. Most of this water has been transformed in the Atlantic to deep water.

Monitoring and forecasting of the state of the Atlantic Ocean for civil and economic purpose is a major objective of EuroGOOS. The aim of this presentation is to remind first the scientific and societal benefits of forecasting the Atlantic, and second, the reasons why we consider that these forecasts are feasible over the Atlantic basin. The forecasting systems already operated in real time in Europe are then briefly described. And the outline of a proposal for an Atlantic Pilot Experiment (APE) is presented: objectives, strategy, and possible agenda, compatible with the planning of the international GODAE Experiment.

In this note we attempt to identify the main developments in data assimilation and ecosystem modelling that must be made in the next few years to build an efficient coastal zone monitoring and prediction system. By the coastal zone we mean the oceans along and sometimes outside the continental margins which may be of particular interest for commercial utilisation, say, within the fishing and/or oil industry. As an example this includes most of the Nordic Seas and the Mediterranean but excludes the major part of the Atlantic basin. Various candidates for the data assimilation methodologies are discussed in addition to presenting the status of current data assimilation systems for Ocean General Circulation Models (OGCMs). The use of data assimilation methods for models of the marine ecosystem is far less developed and a significant effort needs to be invested to implement and examine various assimilation techniques with such models. In addition, there is an urgent need for making observations of ecosystem variables available on a regular basis. The high spatial and temporal coverage which is needed in data assimilation suggest that remotely sensed observations will be crucial, e.g. from ocean color sensors.

Living radiolarians in the Atlantic are indicative of specific water masses. Radiolarian skeletons occur only in the upper few centimeters of late Neogene sediments over most of the mid and lower latitudes of the Atlantic. This is in contrast to common occurrences of radiolarians in the sediments of these latitudes during much of the Paleogene and early Neogene. Paleogene to early Neogene radiolarian biostratigraphies are cosmopolitan due to the pan-tropical oceanic connection. Isolation of the Atlantic starting in Mid-Miocene resulted in changes in siliceous sedimentation and the development of provincial radiolarian faunas. The development of a lew cosmopolitan radiolarian zonation based on tropical submergent forms may aid in interoceanic warm water correlations.

Clay minerals of ancient marine deposits are sensitive indicators for the reconstruction of the history of oceans and of the main stages of their paleogeographical and paleohydrological evolution. This paper presents an example illustrating the accuracy of such tracers for this purpose. It concerns mineralogical studies of 400 samples of Cenozoic deposits collected during two legs of the International Project of Deep Sea Drilling (IPOD) in the North-East Atlantic (leg 47B - W. of the Iberian Peninsula; leg 48-Rockall region W. of Great Britain). The mineralogical composition of the deposits makes it possible to trace, for different periods, the origin and dispersion paths of detrital materials, climatic conditions of weathering in adjacent continental areas and environmental characteristics of sedimentary basins. An important fact is the generally new aspect of the mineralogy of deposits at the Eocene/Oligocene boundary which clearly denotes the occurence of a major hydrodynamic event. It marks the establishment of the system of thermohaline circulation of the modern Atlantic Ocean, when cold dense waters derived from northern regions began to sink to the bottom of the North Atlantic Basin and bring towards the South clay fractions generated by weathering in cold climatic areas.

For most of Lower Cretaceous time, North Atlantic ostracod faunas are only well-developed in the Eastern area and our knowledge is one-sided. Marine transgression and the extension of deposition in the Albian and Upper Cretaceous gave excellent faunas on both sides of the Atlantic and the Basin appears ‘two-sided’. Besides being stratigraphically useful, the ostracods provide ecological information on factors such as salinity, temperature and migration.

Marine Jurassic sediments of the Atlantic Basin are widely developed in the eastern borderland region of the North Atlantic. Here, warm shallow seas supported a rich and varied ostracod fauna—over 200 species being found in the English Bathonian alone. This region is regarded as being one of the major areas in the development and evolution of Post-Palaeozoic Ostracoda. The eastern borderlands may be divided into a northern European (epicontinental sea) Province, a deeper water Tethyan Province and a southern North African province. The South Atlantic Basin was not developed at that time. On the western borders of the North Atlantic Basin Jurassic sediments are present along the east coast of Greenland and offshore along the North American continent—ostracods having iffinities with the epicontinental European faunas are present off Canada, while deep water ostracods, in part comparable with tethyan species from Italy, are present off U.S.A.; shallower water faunas are recorded from the Gulf Coast region (American Province). Biostratigraphically important ostracod genera of the epicontinental provinces belong to three families: the Progonocytheridae, the Schulerideidae and the Protocytheridae. This contrasts with the Jurassic of the Indian Ocean Basin (East African Province) where only the Progonocytheridae is of equal importance. Ostracod genera belonging to other families play an important but subsidiary role in the biostratigraphy of the North Atlantic Jurassic. Fresh to Drackish water ostracods become important in the Middle Jurassic but reach their biostratigraphical acme in the continental deposits of the Upper Jurassic/Lower Cretaceous when the jenus Cypridea achieved a world-wide distribution.

The ostracod fauna of each Cenozoic epoch is described where possible from western Europe (Denmark, Belgium, England, France, N. Spain), the Atlantic seaboard of N. America, Greenland, Rockall, and from the N. Atlantic Basin. No species are known in common to the two sides of the N. Atlantic for the Palaeogene, although genera and species groups indicate some communication. Most Palaeogene ostracods can be related to Cretaceous forebears. The Neogene saw a renewal of the ostracod fauna, with wide and rapid dispersal of genera, with a few species present on both sides of the Atlantic. Fourteen ostracod zones are proposed for the Palaeogene of N.W. Europe, but these cannot be recognised at present in Aquitaine due to provincial differences.

Mesozoic Radiolaria, primarily from Deep Sea Drilling cores, are surveyed. Maps indicate localities, ages, and usefulness of the occurrence. The new Amphipyndax tylotus Zone is defined and the next lower Amphipyndax enesseffi Zone is emended.