Atlantic Basin Tropical Cyclone Activity Research Articles

Implementation of Tropical Cyclone Detection Scheme to CCAM model for Seasonel Tropical Cyclone Prediction over the Vietnam East Sea

Implementation of Tropical Cyclone Detection Scheme to CCAM model for Seasonel Tropical Cyclone Prediction over the Vietnam East Sea

The impacts of column water vapour variability on Atlantic basin tropical cyclone activity

Column water vapour (CWV) in the Tropics is well known to affect tropical deep convection. It has been established that the tropical deep convection required for tropical cyclone formation markedly increases after reaching a critical CWV threshold. Therefore, CWV values below this threshold represent an atmosphere that is too dry for tropical cyclone formation. The interannual variability of the occurrence of this dry air and its impacts on tropical cyclone activity over the Atlantic are examined. CWV empirical orthogonal function (EOF) analysis reveals a dominant mode of interannual variability of dry air events over the tropical North Atlantic, with strong variations over the central and eastern Atlantic between 15°N and 30°N. In the positive (negative) phase of the EOF modes, tropical cyclone activity is reduced (increased) over the Atlantic basin, particularly over the main development region. On the origin of dry air, the Saharan Air Layer does not explain the CWV EOF pattern, but the pattern is shown to be related to large‐scale subsidence in association with enhanced anticyclonic vorticity. The leading mode shows significant correlations to several large‐scale climate oscillations, including the Atlantic Multi‐decadal Oscillation, Pacific Decadal Oscillation, Atlantic Meridional Mode, Pacific North American Pattern, and others. The EOF mode also indicates a relationship to the large‐scale circulation via the Hadley cell. An evaluation of the steering flow for tropical cyclones from the modulation of the subtropical high and the values of deep layer vertical wind shear is consistent with the distribution of tropical cyclone activity in only certain limited areas, suggesting that the impacts of the dry air patterns are required to provide a more complete explanation of the activity.

Modulation of Atlantic Basin Tropical Cyclone Activity by the Madden–Julian Oscillation (MJO) from 1905 to 2011

Abstract The Madden–Julian oscillation (MJO) has been demonstrated to play a role in tropical cyclone (TC) activity around the globe in a number of recent studies. While the impact of the MJO on TCs in the Atlantic basin since the mid-1970s has been well documented, a newly developed 107-yr-long index for the MJO allows for additional analysis of the impacts of the MJO on Atlantic TC activity. TC activity in the Atlantic increases when MJO-related convection is enhanced over Africa and the Indian Ocean, while TC activity in the Atlantic is suppressed when the MJO enhances convection over the western Pacific. This long-term record of the MJO also allows for the analysis of how the MJO’s impacts may be modulated by other climate modes, such as the El Niño–Southern Oscillation (ENSO) over interannual time scales and the Atlantic multidecadal oscillation (AMO) over multidecadal time scales. When climatologically unfavorable conditions such as an El Niño event or a negative AMO phase are present, even TC-favorable MJO conditions are not enough to generate statistically significant increases in TC activity from the long-term average across the Atlantic basin. However, climatologically favorable conditions during a La Niña event or a warm AMO phase act to enhance the modulation of TC activity over the Atlantic basin by the MJO.

El Niño–Southern Oscillation’s Impact on Atlantic Basin Hurricanes and U.S. Landfalls

Abstract El Niño–Southern Oscillation (ENSO) has been shown in many previous papers to impact seasonal levels of Atlantic basin tropical cyclone activity. This paper revisits this relationship by examining a longer period (1900–2009) than has been examined in earlier analyses. Alterations in large-scale climate parameters, especially vertical wind shear, are shown to be the primary reasons why tropical cyclone activity in the Atlantic is reduced in El Niño years. Climate signals are found to be somewhat stronger in the Caribbean than for the remainder of the tropical Atlantic. The focus of the paper then shifts to U.S. landfalls, confirming previous research that U.S. landfalls are reduced in El Niño years. The reduction in landfall frequency is greater along the Florida peninsula and East Coast than it is along the Gulf Coast, especially for major hurricanes. The probability of each state being impacted by a hurricane and major hurricane is given for El Niño, La Niña, and neutral years. The most dramatic probability differences between warm and cold ENSO events lie along the East Coast and, in particular, the state of North Carolina. The relationship between ENSO and the Atlantic multidecadal oscillation (AMO) is also examined. In general, the negative phase of the AMO is characterized by a stronger ENSO modulation signal than a positive phase of the AMO.

Caribbean Islands in a Changing Climate

The Caribbean Sea is the second largest sea in the world, covering an area of approximately 2,515,900 kilometers. The region has the largest number of small island developing states (SIDS) and the ...

Multidecadal Variability in North Atlantic Tropical Cyclone Activity

Abstract Recent increases in Atlantic basin tropical cyclone activity since 1995 and the associated destructive U.S. landfall events in 2004 and 2005 have generated considerable interest into why there has been such a sharp upturn. Natural variability, human-induced global warming, or a combination of both factors, have been suggested. Several previous studies have discussed observed multidecadal variability in the North Atlantic over 25–40-yr time scales. This study, using data from 1878 to the present, creates a metric based on far North Atlantic sea surface temperature anomalies and basinwide North Atlantic sea level pressure anomalies that shows remarkable agreement with observed multidecadal variability in both Atlantic basin tropical cyclone activity and in U.S. landfall frequency.

Revised Prediction of Seasonal Atlantic Basin Tropical Cyclone Activity from 1 August

Abstract Predictions of the remainder of the season’s Atlantic basin tropical cyclone activity from 1 August have been issued by Gray and his colleagues at the Tropical Meteorology Project at Colorado State University since 1984. The original 1 August prediction scheme utilized several predictors, including measures of the stratospheric quasi-biennial oscillation (QBO), West African rainfall, El Niño–Southern Oscillation, and the sea level pressure anomaly and upper-tropospheric zonal wind anomalies in the Caribbean basin. The recent failure of the West African rainfall and QBO relationships with Atlantic hurricanes has led to a general degradation of the original 1 August forecast scheme in recent years. It was decided to revise the scheme using only surface data. The development of the National Centers for Environmental Prediction–National Center for Atmospheric Research reanalysis has provided a vast wealth of globally gridded meteorological and oceanic data from 1948 to the present. In addition, other datasets have been extended back even further (to 1900), which allows for a large independent dataset. These longer-period datasets allow for an extended period of testing of the new statistical forecast scheme. A new prediction scheme has been developed on data from 1949 to 1989 and then tested on two independent datasets. One of these datasets is the 16-yr period from 1990 to 2005, and the other dataset is from 1900 to 1948. This allows for an investigation of the statistical significance over various time periods. The statistical scheme shows remarkable stability over an entire century. The combination of these four predictors explains between 45% and 60% of the variance in net tropical cyclone activity over the following separate time periods: 1900–48, 1949–89, 1949–2005, and 1900–2005. The forecast scheme also shows considerable skill as a potential predictor for giving the probabilities of United States landfall. Large differences in U.S. major hurricane landfall are also observed between forecasts that call for active seasons compared with those that call for inactive seasons.

Recent developments in statistical prediction of seasonal Atlantic basin tropical cyclone activity

Statistical forecasts of Atlantic basin seasonal hurricane activity have been issued since 1984 by the Tropical Meteorology Project at Colorado State University (CSU) headed by William Gray. Since these initial forecasts were developed, considerable improvements in data and statistical techniques have led to improved amounts of skill in both hindcasting and forecasting of seasonal Atlantic basin hurricane activity by CSU as well as other forecast groups including the National Oceanic and Atmospheric Administration and Tropical Storm Risk. Statistical seasonal forecasts derive their skill from atmospheric and oceanic parameters that span the globe. Recent developments in statistical prediction include the development of shorter-period forecasts for the individual months of August, September and October and the issuing of landfall predictions or probabilities. Individual forecast groups generally utilize large-scale atmospheric wind and circulation patterns to issue their landfall forecasts. In addition, landfall probabilities down to the county level for all coastal counties from Brownsville, Texas to Eastport, Maine have recently been made available online. Several forecasting groups are now issuing seasonal forecasts for the Atlantic basin, and it is to be expected that the skill of these forecasts will continue to improve with additional access to improved data and modelling capabilities.

Recent developments in statistical prediction of seasonal Atlantic basin tropical cyclone activity

Statistical forecasts of Atlantic basin seasonal hurricane activity have been issued since 1984 by theTropical Meteorology Project at Colorado State University (CSU) headed by William Gray. Since these initial forecasts were developed, considerable improvements in data and statistical techniques have led to improved amounts of skill in both hindcasting and forecasting of seasonal Atlantic basin hurricane activity by CSU as well as other forecast groups including the National Oceanic and Atmospheric Administration and Tropical Storm Risk. Statistical seasonal forecasts derive their skill from atmospheric and oceanic parameters that span the globe.Recent developments in statistical prediction include the development of shorter-period forecasts for the individual months of August, September and October and the issuing of landfall predictions or probabilities. Individual forecast groups generally utilize large-scale atmospheric wind and circulation patterns to issue their landfall forecasts. In addition, landfall probabilities down to the county level for all coastal counties from Brownsville, Texas to Eastport, Maine have recently been made available online. Several forecasting groups are nowissuing seasonal forecasts for the Atlantic basin, and it is to be expected that the skill of these forecasts will continue to improve with additional access to improved data and modelling capabilities.

A Reassessment of Historical Atlantic Basin Tropical Cyclone Activity, 1700–1855

The chronological table of Atlantic basin tropical cyclones produced by Andres Poey in 1855 is the foundation stone for present-day knowledge of historical Atlantic tropical cyclone activity. Subsequent researchers have used his table and built upon it, rejecting some of his entries, modifying others, and accepting the rest. A re-analysis of the 1700-1855 portion of Poey's original published list was made using historical newspaper accounts, weather diaries, and ships' logbooks. Of the 348 separate entries in Poey's original list, 149 were rejected and 198 accepted. Due to errors in dating and location, and the linking of separate entries as parts of the same storm, only 170 of the 198 accepted entries are unique storms. Thirteen undated storms of the remaining 170 are now dated. The authorities cited by Poey vary in their reliability. Of those cited 10 or more times, there was an average of one incorrect citation for every 3.1 correct citations. The most and least reliable authorities used by Poey are identified. An updated corrected chronology from all published sources is presented and includes 383 unique storms through 1855.

Forecasting September Atlantic Basin Tropical Cyclone Activity

September is the most active month for Atlantic basin tropical cyclone activity with about 50% of all hurricane activity occurring during this month. Utilizing National Centers for Environmental Prediction‐National Center for Atmospheric Research (NCEP‐NCAR) reanalysis data, a prediction scheme for forecasting September tropical cyclone activity has been developed. Based on hindcasting results from 1950 to 2000, 30%‐75% of the variance for most tropical cyclone parameters can be hindcast by the end of July. This hindcast skill improves to 45%‐ 75% by the end of August. Similarly, cross-validated hindcast skill explains from 20% to 65% for most variables by the end of July, improving to 30%‐65% by the end of August. Simple least squared linear regression was utilized to calculate hindcast skill, and variables were selected that explained the largest degree of variance when combined with the other predictors in the scheme. These predictors tend to be global in nature and include zonal and meridional wind at 200 and 1000 mb and sea level pressure measurements at various global locations.

Predicting Atlantic Basin Seasonal Tropical Cyclone Activity by 1 August

Abstract More than 90% of all seasonal Atlantic tropical cyclone activity typically occurs after 1 August. A strong predictive potential exists that allows seasonal forecasts of Atlantic basin tropical cyclone activity to be issued by 1 August, prior to the start of the active portion of the hurricane season. Predictors include June-July meteorological information of the stratospheric quasi-biennial oscillation (QBO), West African rainfall, the El Nino-Southern Oscillation (ENSO) as well as sea level pressure anomalies (SLPA), and the upper-tropospheric zonal-wind anomalies (ZWA) in the Caribbean basin. Use of a combination of these global and regional predictors provides a basis for making cross-validated (jackknifed) 1 August hindcasts of subsequent Atlantic seasonal tropical cyclone activity that show substantial skill over climatology. This relationship is demonstrated in 41 years of hindcasts of the 1950-90 seasons. It is possible to independently explain more than 60% of the year-to-year variability...