Meteorological factors affecting the speed of movement and related impacts of extratropical cyclones along the U.S. east coast (original) (raw)
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Climatic Change, 2019
We investigate the impact of climate change on the storm surges induced by extratropical cyclones (ETCs) between November and March. We quantify changes to the storm surge between a historical period (1979-2004) and a future period during the mid to late twenty-first century (2054-2079) for a number of major coastal cities in the Northeastern United States. Observed water levels are analyzed to estimate storm surges induced by ETCs during the historical period. A hydrodynamic model is utilized to simulate storm surges induced by ETCs projected for the future climate by seven global climate models. The biases in the hydrodynamic and climate models are calculated and removed from the simulated surge heights. Statistical methods, including the peaks-over-threshold method, are applied to estimate the storm surge return levels. We find that future projections based on most of the climate models indicate relatively small effects of climate change on ETC storm surges. The weighted-average projections over all climate models show a small increase in storm surge return levels (less than 7% increase in 10-and 50-year surge heights). However, uncertainties exist among the climate models and projections from one climate model show a substantial increase in the storm surge return levels (up to 27% and 36% increase in 10-and 50-year surge heights, respectively). These uncertainties, and likely the larger impact of sea level rise, should be accounted for in projecting the risk posted by ETC flooding.
Advances in Atmospheric Sciences, 2002
The interannual variability of the Atlantic tropical cyclone (TC) frequency is well known. Separately, recent studies have also suggested that a much longer, multidecadal (40-60 year) trend might be emerging from the recent increase in Atlantic TC activity. However, the overall structure of the intrinsic frequencies (or temporal modes) of Atlantic TC activity is not yet known. The focus of this study is to systematically analyze the intrinsic frequencies of Atlantic TC activity using hurricane and tropical storm landfall data collected along the southeast coast (SEC) of the United States. Based on an Empirical Mode Decomposition (EMD) analysis of the frequency of landfall TCs along the SEC from 1887-1999, we have found that Atlantic TC activity has four primary, temporal modes. The interannual and multidecadal modes reported in the published literature are two such modes. After identifying all primary modes, the relative importance of each mode and its physical cause can be analyzed. For example, the most energetic mode is the interannual mode (2-7 year period). This mode is known to be associated with the 2-7 year El Nifio / La Ni fia cycle. The average number of annual "landfalling TCs along the SEC decreased by 24% during El Nifio years, but did not show significant increase during weak and moderate La Nifia years. However, intense La Nifia years were generally associated with more than average landfalling TCs along the SEC. The effects of El Nifio and La Nifia also became more significant when only hurricanes were considered. The significance of the effects of El Nifio and La Nifia on landfalling TCs and hurricanes in different US southeast coastal states showed significant differences.
Nat. Wea. Dig, 2000
The investigation of the effect of El Niño-related variability on hurricane activity has been a popular topic of study. Studies have shown that there are fewer Atlantic Ocean basin hurricanes during an El Nino year than during a La Nina year. Various atmospheric and oceanic parameters that influence hurricane development become significantly altered during an El Niño event, leading to suppressed easterly wave development and growth. The effect of the El Niño/La Niña cycle on hurricane intensity, however, is not straightforward. Studies addressing the interannual variability of hurricane intensity have captured far less attention than the more generalized subject of hurricane occurrence. This study examined the interannual variability of hurricane intensity (measured as wind speed and interpreted through the Saffir-Simpson Scale) from 1938 through 1999. These data were then compared with the occurrence of El Niño/La Niña events as defined using the Japan Meteorological Association (JMA) index. El Nino/La Nina variability superimposed on variability associated with the North Pacific Oscillation (NPO) was also examined here. Not surprisingly, during an El Niño year the intensity of Atlantic hurricanes was found to be weaker than during a neutral year or a La Niña year. There were also significant differences found in hurricane intensity between El Nino and La Nina years when the NPO was in phase 1, rather than when the NPO was in phase 2. Finally, this study also examined the interannual variation in hurricane intensity by genesis region (i.e. the eastern and western Atlantic Ocean Basins, the Caribbean, and the Gulf of Mexico).
Changes in U.S. East Coast Cyclone Dynamics with Climate Change
Journal of Climate, 2015
Previous studies investigating the impacts of climate change on extratropical cyclones have primarily focused on changes in the frequency, intensity, and distribution of these events. Fewer studies have directly investigated changes in the storm-scale dynamics of individual cyclones. Precipitation associated with these events is projected to increase with warming owing to increased atmospheric water vapor content. This presents the potential for enhancement of cyclone intensity through increased lower-tropospheric diabatic potential vorticity generation. This hypothesis is tested using the Weather Research and Forecasting Model to simulate individual wintertime extratropical cyclone events along the United States East Coast in present-day and future thermodynamic environments. Thermodynamic changes derived from an ensemble of GCMs for the IPCC Fourth Assessment Report (AR4) A2 emissions scenario are applied to analyzed initial and lateral boundary conditions of observed strongly developing cyclone events, holding relative humidity constant. The perturbed boundary conditions are then used to drive future simulations of these strongly developing events. Present-to-future changes in the storm-scale dynamics are assessed using Earth-relative and storm-relative compositing. Precipitation increases at a rate slightly less than that dictated by the Clausius-Clapeyron relation with warming. Increases in cyclone intensity are seen in the form of minimum sea level pressure decreases and a strengthened 10-m wind field. Amplification of the low-level jet occurs because of the enhancement of latent heating. Storm-relative potential vorticity diagnostics indicate a strengthening of diabatic potential vorticity near the cyclone center, thus supporting the hypothesis that enhanced latent heat release is responsible for this regional increase in future cyclone intensity.
Climatology and Interannual Variability of North Atlantic Hurricane Tracks
Journal of Climate, 2005
The spatial and temporal variability of North Atlantic hurricane tracks and its possible association with the annual hurricane landfall frequency along the U.S. East Coast are studied using principal component analysis (PCA) of hurricane track density function (HTDF). The results show that, in addition to the well-documented effects of the El Niño-Southern Oscillation (ENSO) and vertical wind shear (VWS), North Atlantic HTDF is strongly modulated by the dipole mode (DM) of Atlantic sea surface temperature (SST) as well as the North Atlantic Oscillation (NAO) and Arctic Oscillation (AO). Specifically, it was found that Atlantic SST DM is the only index that is associated with all top three empirical orthogonal function (EOF) modes of the Atlantic HTDF. ENSO and tropical Atlantic VWS are significantly correlated with the first and the third EOF of the HTDF over the North Atlantic Ocean. The second EOF of North Atlantic HTDF, which represents the "zonal gradient" of North Atlantic hurricane track density, showed no significant correlation with ENSO or with tropical Atlantic VWS. Instead, it is associated with the Atlantic SST DM, and extratropical processes including NAO and AO. Since for a given hurricane season, the preferred hurricane track pattern, together with the overall basinwide hurricane activity, collectively determines the hurricane landfall frequency, the results provide a foundation for the construction of a statistical model that projects the annual number of hurricanes striking the eastern seaboard of the United States.
Impacts of non-canonical El Niño patterns on Atlantic hurricane activity
Geophysical Research Letters, 2012
The impact of non-canonical El Niño patterns, typically characterized by warmer than normal sea surface temperatures (SSTs) in the central tropical Pacific, on Atlantic tropical cyclone (TC) is explored by using composites of key Atlantic TC indices and tropospheric vertical wind shear over the Atlantic main development region (MDR). The highlight of our major findings is that, while the canonical El Niño pattern has a strong suppressing influence on Atlantic TC activity, non-canonical El Niño patterns considered in this study, namely central Pacific warming, El Niño Modoki, positive phase Trans-Niño, and positive phase Pacific meridional mode, all have insubstantial impact on Atlantic TC activity. This result becomes more conclusive when the impact of MDR SST is removed from the Atlantic TC indices and MDR wind shear by using the method of linear regression. Further analysis suggests that the tropical Pacific SST anomalies associated with the non-canonical El Niño patterns are not strong enough to cause a substantial warming of the tropical troposphere in the Atlantic region, which is the key factor that increases the wind shear and atmospheric static stability over the MDR. During the recent decades, the non-canonical El Niños have been more frequent while the canonical El Niño has been less frequent. If such a trend continues in the future, it is expected that the suppressing effect of El Niño on Atlantic TC activity will diminish and thus the MDR SST will play a more important role in controlling Atlantic TC activity in the coming decades.
Spatial and temporal variability of coastal storms in the North Atlantic Basin
Marine Geology, 2004
Over the past three to four decades, there has been a growing awareness of the important controls exerted by large-scale meteorological events on coastal systems. For example, definitive links are being established between short-term (timescales of 5 -10 years) beach dynamics and storm frequency. This paper assesses temporal variability of coastal storms (both tropical and extratropical) and the wave climatology in the North Atlantic Basin (NAB), including the Gulf of Mexico. With both storm types, the empirical record shows decadal scale variability, but neither demonstrates highly significant trends that can be linked conclusively to natural or anthropogenic factors. Tropical storm frequencies have declined over the past two or three decades, which is perhaps related to recent intense and prolonged El Niños. Some forecasts predict higher frequencies of tropical storms like that experienced from the 1920s to the 1960s to occur in coming decades. Results from general circulation models (GCMs) suggest that overall frequencies of tropical storms could decrease slightly, but that there is potential for the generation of more intense hurricanes. These data have important implications for the short-term evolution of coastal systems.
A Climatology of Inland Winds from Tropical Cyclones for the Eastern United States
Journal of Applied Meteorology and Climatology, 2010
Tropical cyclones pose a significant threat to life and property along coastal regions of the United States. As these systems move inland and dissipate, they can also pose a threat to life and property, through heavy rains, high winds, and other severe weather such as tornadoes. While many studies have focused on the impacts from tropical cyclones on coastal counties of the United States, this study goes beyond the coast and examines the impacts caused by tropical cyclones on inland locations. Using geographical information system software, historical track data are used in conjunction with the radial maximum extent of the maximum sustained winds at 34-, 50-, and 64-kt (1 kt ' 0.5 m s 21 ) thresholds for all intensities of tropical cyclones and overlaid on a 30-km equal-area grid that covers the eastern half of the United States. The result is a series of maps with frequency distributions and an estimation of return intervals for inland tropical storm-and hurricane-force winds. Knowing where the climatologically favored areas are for tropical cyclones, combined with a climatological expectation of the inland penetration frequency of these storms, can be of tremendous value to forecasters, emergency managers, and the public.