Fujiwhara effect

Abstract: The influence of vertical wind shear on the azimuthal distribution of cloud-to-ground lightning in tropical cyclones was examined using flash locations from the National Lightning Detection Network. The study covers 35 Atlantic basin tropical cyclones from 1985–99 while they were over land and within 400 km of the coast over water. A strong correlation was found between the azimuthal distribution of flashes and the direction of the vertical wind shear in the environment. When the magnitude of the vertical shear exceeded 5 m s−1, more than 90% of flashes occurred downshear in both the storm core (defined as the inner 100 km) and the outer band region (r = 100–300 km). A slight preference for downshear left occurred in the storm core, and a strong preference for downshear right in the outer rainbands. The results were valid both over land and water, and for depression, storm, and hurricane stages. It is argued that in convectively active tropical cyclones, deep divergent circulations oppose the ver...

Abstract: In this paper the climatology and structure of, and possible reasons for, tropical cyclones of different sizes are examined. The climatology of tropical cyclone sizes confirms that tropical cyclones of the western North Pacific are characteristically twice as large as their Atlantic counterparts, and also reveals that the typical size of tropical cyclones varies seasonally and regionally and is only weakly correlated with cyclone intensity (maximum surface wind or minimum surface pressure). Rawinsonde composities of large and small tropical cyclones show that large cyclones have much more relative angular momentum (RAM) than small cyclones, while the differences in RAM between intense and weaker cyclones of equivalent size are less. Some of the implications of this observance are discussed, and a hypothesis that cyclones grow as a result of an increased convergence of angular momentum forced by their environment is presented.

Abstract: The ability of the climate models participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5) to simulate North Atlantic extratropical cyclones in winter [December–February (DJF)] and summer [June–August (JJA)] is investigated in detail. Cyclones are identified as maxima in T42 vorticity at 850 hPa and their propagation is tracked using an objective feature-tracking algorithm. By comparing the historical CMIP5 simulations (1976–2005) and the ECMWF Interim Re-Analysis (ERA-Interim; 1979–2008), the authors find that systematic biases affect the number and intensity of North Atlantic cyclones in CMIP5 models. In DJF, the North Atlantic storm track tends to be either too zonal or displaced southward, thus leading to too few and weak cyclones over the Norwegian Sea and too many cyclones in central Europe. In JJA, the position of the North Atlantic storm track is generally well captured but some CMIP5 models underestimate the total number of cyclones. The dynamical intensity of cyclone...

Abstract: Structure, Formation and Movement of Tropical Cyclones Role of Ocean in Tropical Cyclone Structure and Formation Extratropical Transition of Tropical Cyclones Near-Surface-Based, Airborne and Satellite Observations of Tropical Cyclones Climate Variability and Seasonal Forecasts of Tropical Cyclones Tropical Cyclones and Climate Change Track and Structure Forecasts of Tropical Cyclones Storm Surges and Rainfall Associated with Tropical Cyclones Mitigation of Disasters Associated with Tropical Cyclones.