On the Impact of Tropical Cyclones on Rossby Wave Packets: A Climatological Perspective
TL;DR: In this paper, the authors investigated the impact of recurving tropical cyclones (TCs) on the amplitude and frequency of synoptic-scale Rossby wave packets (RWPs) over a 30-year period.
Abstract: Many studies have highlighted the importance of recurving tropical cyclones (TCs) in triggering Rossby waves. This study investigates the impact of western North Pacific (WNP), south Indian Ocean, and North Atlantic recurving TCs on the amplitude and frequency of synoptic-scale Rossby wave packets (RWPs) over a 30-yr period. The results indicate a significant increase of RWP frequency downstream of WNP and south Indian Ocean TCs. A statistically significant RWP amplitude anomaly downstream of these TCs suggests that RWPs, which are associated with TCs, are stronger than those that generally occur in midlatitudes. North Atlantic TCs do not seem to be associated with a statistically significant increase in RWP frequency and amplitude downstream.Processes that contribute to Rossby wave amplification are identified by creating composites for WNP TCs with and without downstream development. Potential vorticity, eddy kinetic energy, and quasigeostrophic forcing diagnostics highlight dynamical mechanisms...
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TL;DR: In this paper, a review of the literature on upper-tropospheric transient wave packets along the midlatitude jet stream is presented, with an emphasis on developments during the last 15 years.
Abstract: Rossby wave packets (RWPs) are Rossby waves for which the amplitude has a local maximum and decays to smaller values at larger distances. This review focuses on upper-tropospheric transient RWPs along the midlatitude jet stream. Their central characteristic is the propagation in the zonal direction as well as the transfer of wave energy from one individual trough or ridge to its downstream neighbor, a process called “downstream development.” These RWPs sometimes act as long-range precursors to extreme weather and presumably have an influence on the predictability of midlatitude weather systems. The paper reviews research progress in this area with an emphasis on developments during the last 15 years. The current state of knowledge is summarized including a discussion of the RWP life cycle as well as Rossby waveguides. Recent progress in the dynamical understanding of RWPs has been based, in part, on the development of diagnostic methods. These methods include algorithms to identify and track RWPs ...
137 citations
Cites background from "On the Impact of Tropical Cyclones ..."
...Yet, the traditional eddy life cycle may well be applicable to the evolution of the zonally averaged behavior, which represents the averaged effect over a single RWP or multiple RWPs (Randel and Stanford 1985; Chang 2005b)....
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University of Wisconsin–Milwaukee1, Mississippi State University2, Atlantic Oceanographic and Meteorological Laboratory3, Silver Spring Networks4, Embry–Riddle Aeronautical University5, University at Albany, SUNY6, National Center for Atmospheric Research7, University of São Paulo8, United States Naval Research Laboratory9, University of Arizona10, ETH Zurich11, McGill University12, Florida State University13, Meteorological College14, Karlsruhe Institute of Technology15, Environment Canada16, Bedford Institute of Oceanography17, Monash University18, University of Mainz19, University of New South Wales20, Pennsylvania State University21
TL;DR: Extratropical transition (ET) is the process by which a tropical cyclone, upon encountering a baroclinic environment and reduced sea surface temperature at higher latitudes, transforms into an extraspatial cyclone.
Abstract: Extratropical transition (ET) is the process by which a tropical cyclone, upon encountering a baroclinic environment and reduced sea surface temperature at higher latitudes, transforms into an extratropical cyclone. This process is influenced by, and influences, phenomena from the tropics to the midlatitudes and from the meso- to the planetary scales to extents that vary between individual events. Motivated in part by recent high-impact and/or extensively observed events such as North Atlantic Hurricane Sandy in 2012 and western North Pacific Typhoon Sinlaku in 2008, this review details advances in understanding and predicting ET since the publication of an earlier review in 2003. Methods for diagnosing ET in reanalysis, observational, and model-forecast datasets are discussed. New climatologies for the eastern North Pacific and southwest Indian Oceans are presented alongside updates to western North Pacific and North Atlantic Ocean climatologies. Advances in understanding and, in some cases, mode...
113 citations
Cites background from "On the Impact of Tropical Cyclones ..."
...Extratropical transition is not evenly distributed throughout the WNP typhoon season, with the largest number of events found in September (Klein et al. 2000; Kitabatake 2011; Archambault et al. 2013; Quinting and Jones 2016)....
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25 May 2000
TL;DR: In this paper, the authors simulated the impact of the strength of the midlatitude circulation trough without changing its phasing with the tropical cyclone and found that the peak intensity of the extratropical cyclone following the extarropical transition is strongly dependent on the phasing, which leads to different degrees of interaction with the mid-latitude baroclinic zone.
Abstract: Abstract Whether the tropical cyclone remnants will become a significant extratropical cyclone during the reintensification stage of extratropical transition is a complex problem because of the uncertainty in the tropical cyclone, the midlatitude circulation, the subtropical anticyclone, and the nonlinear interactions among these systems. In a previous study, the authors simulated the impact of the strength of the midlatitude circulation trough without changing its phasing with the tropical cyclone. In this study, the impact of phasing is simulated by fixing the initial position and amplitude of the midlatitude trough and varying the initial position of the tropical cyclone. The peak intensity of the extratropical cyclone following the extratropical transition is strongly dependent on the phasing, which leads to different degrees of interaction with the midlatitude baroclinic zone. Many aspects of the simulated circulation, temperature, and precipitation fields appear quite realistic for the reintensifyin...
89 citations
TL;DR: In this article, the role of diabatic outflow in midlatitude flow amplification was highlighted in the context of a review of the physical and dynamical processes involved in extratropical transition.
Abstract: Recurving tropical cyclones (TCs) undergoing extratropical transition (ET) may substantially modify the large-scale midlatitude flow pattern. This study highlights the role of diabatic outflow in midlatitude flow amplification within the context of a review of the physical and dynamical processes involved in ET. Composite fields of 12 western North Pacific ET cases are used as initial and boundary conditions for high-resolution numerical simulations of the North Pacific–North American sector with and without the TC present. It is demonstrated that a three-stage sequence of diabatic outflow associated with different weather systems is involved in triggering a highly amplified midlatitude flow pattern: 1) preconditioning by a predecessor rain event (PRE), 2) TC–extratropical flow interaction, and 3) downstream flow amplification by a downstream warm conveyor belt (WCB). An ensemble of perturbed simulations demonstrates the robustness of these stages. Beyond earlier studies investigating PREs, recurv...
81 citations
TL;DR: In this article, the role of diabatic processes, in particular the release of latent heating in strongly ascending airstreams, play in the dynamics and spatio-temporal variability of blocking in a detailed 38-year global climatological analysis.
Abstract: Atmospheric blocking represents an important aspect of the mid-latitude weather variability, but the different processes contributing to its formation and maintenance are not yet fully understood. This study investigates the role that diabatic processes, in particular the release of latent heating in strongly ascending airstreams, play in the dynamics and spatio-temporal variability of blocking in a detailed 38-year global climatological analysis. The results show that the formation and (re-)intensification of blocking are often preceded by latent heating connected to upstream baroclinic developments. While the importance of latent heating varies considerably between individual blocking events and different regions, in particular between ocean and continents, latent heating is generally most important during onset and in more intense and larger blocks. The episodic nature of latent heating during the blocking life cycle, associated with a series of transient cyclones approaching the blocking, can contribute to both the high- (fast onset and fluctuation in intensity and size) and low-frequency (maintenance and quasi-stationarity during maturation phase) properties of blocking anticyclones and provide the required flow amplification in addition to dry-dynamical interaction between synoptic eddies and blocking. This amplification results from a combination of the direct injection of anticyclonic air into the upper-troposphere within cross-isentropic ascending airstreams, setting up large-scale anticyclonic PV anomalies, and the advection of PV by the enhanced divergent outflow at the tropopause (indirect effect). This divergent outflow on the western flank of the blocking anticyclone interacts with the upper-level PV gradient and leads to a westward amplification of the ridge, diminishing the tendency for dissipation and the eastward advection by the background flow, thus contributing to blocking stationarity. Taking into account such diabatic mechanisms in blocking dynamics will be important to improve predictions of blocking and assess future changes in the extratropical large-scale circulation.
78 citations
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TL;DR: ERA-Interim as discussed by the authors is the latest global atmospheric reanalysis produced by the European Centre for Medium-Range Weather Forecasts (ECMWF), which will extend back to the early part of the twentieth century.
Abstract: ERA-Interim is the latest global atmospheric reanalysis produced by the European Centre for Medium-Range Weather Forecasts (ECMWF). The ERA-Interim project was conducted in part to prepare for a new atmospheric reanalysis to replace ERA-40, which will extend back to the early part of the twentieth century. This article describes the forecast model, data assimilation method, and input datasets used to produce ERA-Interim, and discusses the performance of the system. Special emphasis is placed on various difficulties encountered in the production of ERA-40, including the representation of the hydrological cycle, the quality of the stratospheric circulation, and the consistency in time of the reanalysed fields. We provide evidence for substantial improvements in each of these aspects. We also identify areas where further work is needed and describe opportunities and objectives for future reanalysis projects at ECMWF. Copyright © 2011 Royal Meteorological Society
22,055 citations
TL;DR: In this article, the Lagrangian conservation principle for potential vorticity and potential temperature is extended to take the lower boundary condition into account, where the total mass under each isentropic surface is specified.
Abstract: The two main principles underlying the use of isentropic maps of potential vorticity to represent dynamical processes in the atmosphere are reviewed, including the extension of those principles to take the lower boundary condition into account. the first is the familiar Lagrangian conservation principle, for potential vorticity (PV) and potential temperature, which holds approximately when advective processes dominate frictional and diabatic ones. the second is the principle of ‘invertibility’ of the PV distribution, which holds whether or not diabatic and frictional processes are important. the invertibility principle states that if the total mass under each isentropic surface is specified, then a knowledge of the global distribution of PV on each isentropic surface and of potential temperature at the lower boundary (which within certain limitations can be considered to be part of the PV distribution) is sufficient to deduce, diagnostically, all the other dynamical fields, such as winds, temperatures, geopotential heights, static stabilities, and vertical velocities, under a suitable balance condition. the statement that vertical velocities can be deduced is related to the well-known omega equation principle, and depends on having sufficient information about diabatic and frictional processes. Quasi-geostrophic, semigeostrophic, and ‘nonlinear normal mode initialization’ realizations of the balance condition are discussed. an important constraint on the mass-weighted integral of PV over a material volume and on its possible diabatic and frictional change is noted.
Some basic examples are given, both from operational weather analyses and from idealized theoretical models, to illustrate the insights that can be gained from this approach and to indicate its relation to classical synoptic and air-mass concepts. Included are discussions of (a) the structure, origin and persistence of cutoff cyclones and blocking anticyclones, (b) the physical mechanisms of Rossby wave propagation, baroclinic instability, and barotropic instability, and (c) the spatially and temporally nonuniform way in which such waves and instabilities may become strongly nonlinear, as in an occluding cyclone or in the formation of an upper air shear line. Connections with principles derived from synoptic experience are indicated, such as the ‘PVA rule’ concerning positive vorticity advection on upper air charts, and the role of disturbances of upper air origin, in combination with low-level warm advection, in triggering latent heat release to produce explosive cyclonic development. In all cases it is found that time sequences of isentropic potential vorticity and surface potential temperature charts—which succinctly summarize the combined effects of vorticity advection, thermal advection, and vertical motion without requiring explicit knowledge of the vertical motion field—lead to a very clear and complete picture of the dynamics. This picture is remarkably simple in many cases of real meteorological interest. It involves, in principle, no sacrifices in quantitative accuracy beyond what is inherent in the concept of balance, as used for instance in the initialization of numerical weather forecasts.
2,763 citations
TL;DR: The International Best Track Archive for Climate Stewardship (IBTrACS) project as discussed by the authors collects the historical tropical cyclone best-track data from all available Regional Specialized Meteorological Centers (RSMCs) and other agencies, combine the disparate datasets into one product, and disseminate in formats used by the tropicalcyclone community.
Abstract: The goal of the International Best Track Archive for Climate Stewardship (IBTrACS) project is to collect the historical tropical cyclone best-track data from all available Regional Specialized Meteorological Centers (RSMCs) and other agencies, combine the disparate datasets into one product, and disseminate in formats used by the tropical cyclone community Each RSMC forecasts and monitors storms for a specific region and annually archives best-track data, which consist of information on a storm's position, intensity, and other related parameters IBTrACS is a new dataset based on the best-track data from numerous sources Moreover, rather than preferentially selecting one track and intensity for each storm, the mean position, the original intensities from the agencies, and summary statistics are provided This article discusses the dataset construction, explores the tropical cyclone climatology from IBTrACS, and concludes with an analysis of uncertainty in the tropical cyclone intensity record
1,733 citations
TL;DR: In this article, a simple, concise, one-term representation of the geostrophic forcing of age-ostrophic motion is presented. But this is achieved at the expense of neglecting another term which is dominant in frontal regions.
Abstract: In the conventional quasi-geostrophic form of the ‘omega’-equation, the forcing of vertical velocity is usually expressed as the sum of two terms associated respectively with vorticity and temperature advection. Consideration of each term in isolation is misleading and there can be a large degree of cancellation. On the other hand, in Sutcliffe's development theory, this forcing is, in effect, represented by a single term. However, this is achieved at the expense of neglecting another term which is dominant in frontal regions. An investigation, based upon the governing equations, of the manner in which geostrophic balance tends to destroy itself, reveals a simple, concise, one-term representation of the geostrophic forcing of ageostrophic motion. Many of the traditional synoptic rules are then simple deductions from this theory. An application of the theory in the case of a rapidly developing system is demonstrated using a 700mb chart.
495 citations
Ludwig Maximilian University of Munich1, Naval Postgraduate School2, Meteorological Service of Canada3, State University of New York System4, Dartmouth College5, Pennsylvania State University6, Florida State University7, Bureau of Meteorology8, European Centre for Medium-Range Weather Forecasts9, Embry–Riddle Aeronautical University10
TL;DR: In this article, the challenges associated with forecasting extratropical transition are described in terms of the forecast variables (track, intensity, surface winds, precipitation) and their impacts (flooding, bush fires, ocean response).
Abstract: A significant number of tropical cyclones move into the midlatitudes and transform into extratropical cyclones. This process is generally referred to as extratropical transition (ET). During ET a cyclone frequently produces intense rainfall and strong winds and has increased forward motion, so that such systems pose a serious threat to land and maritime activities. Changes in the structure of a system as it evolves from a tropical to an extratropical cyclone during ET necessitate changes in forecast strategies. In this paper a brief climatology of ET is given and the challenges associated with forecasting extratropical transition are described in terms of the forecast variables (track, intensity, surface winds, precipitation) and their impacts (flooding, bush fires, ocean response). The problems associated with the numerical prediction of ET are discussed. A comprehensive review of the current understanding of the processes involved in ET is presented. Classifications of extratropical transition ...
481 citations