The Experts below are selected from a list of 252 Experts worldwide ranked by ideXlab platform
James B Elsner - One of the best experts on this subject based on the ideXlab platform.
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A Statistical Analysis of the Frequency of United States and Eastern North Pacific Hurricanes Related to Solar Activity
Hurricanes and Climate Change, 2010Co-Authors: Robert E. Hodges, James B ElsnerAbstract:In this chapter, we examine the statistical relationship between the frequency of United States and eastern North Pacific (ENP) Hurricanes and the solar cycle. First, a relationship between the probability of a Hurricane and sunspot numbers is shown that is conditional on ocean temperature. For years of above normal ocean temperatures, the probability of three or more Hurricanes in the United States decreases from 40% to 20% as sunspot numbers increase. Second, a solar index that tracks intraseasonal variability in sunspot numbers is constructed and correlated with Hurricane activity. The index is inversely related to the total sunspot numbers (SSN) and is significantly correlated with the probability of Hurricanes and Major Hurricanes affecting the United States. The chances of at least one U.S. Hurricane in the lowest and highest SSN anomaly season are 25% and 64%, respectively. The solar index is then used as a predictor of Major Hurricane frequency over the ENP where it is found that the chance of at least six Major ENP Hurricanes increases from about 1% when the solar index lowest to 28% when the index is highest.
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spatial variations in Major u s Hurricane activity statistics and a physical mechanism
Journal of Climate, 2000Co-Authors: James B Elsner, Bethany KocherAbstract:The authors provide a statistical and physical basis for understanding regional variations in Major Hurricane activity along the U.S. coastline on long timescales. Current statistical models of Hurricane activity are focused on the frequency of events over the entire North Atlantic basin. The exception is the lead author’s previous work, which models the occurrence of Hurricanes over the Caribbean Sea, Gulf of Mexico, and the southeast U.S. coast separately. Here the authors use statistics to analyze data from historical and paleoclimatic records to expand this work. In particular, an inverse correlation in Major Hurricane activity across latitudes at various timescales is articulated. When activity is above normal at high latitudes it tends to be below normal at low latitudes and vice versa. Past research, paleoclimatic records, and historical data hint at the potential of using the North Atlantic oscillation (NAO) as an indicator of where storms will likely track over long timescales. An excited (relaxed) NAO is associated with higher (lower) latitude recurving (nonrecurving) storms. The Gulf (East) Coast is more susceptible to a Major Hurricane strike during a relaxed (excited) NAO.
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changes in the rates of north atlantic Major Hurricane activity during the 20th century
Geophysical Research Letters, 2000Co-Authors: James B Elsner, Thomas H JaggerAbstract:The authors document and explain changes in the rates of North Atlantic Major Hurricanes over the 20th century. A change-point analyses identifies two contrasting regimes of activity. The regimes have significantly different occurrence rates that coincide with changes in the climate over the extratropical North Atlantic. In conjunction with the recent Arctic warming and a relaxation of the North Atlantic oscillation, it is speculated that we are beginning a new period of greater Major Hurricane activity.
Kerry A Emanuel - One of the best experts on this subject based on the ideXlab platform.
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air sea enthalpy and momentum exchange at Major Hurricane wind speeds observed during cblast
Journal of the Atmospheric Sciences, 2012Co-Authors: Michael M Bell, Michael T Montgomery, Kerry A EmanuelAbstract:AbstractQuantifying air–sea exchanges of enthalpy and momentum is important for understanding and skillfully predicting tropical cyclone intensity, but the magnitude of the corresponding wind speed–dependent bulk exchange coefficients is largely unknown at Major Hurricane wind speeds greater than 50 m s−1. Since direct turbulent flux measurements in these conditions are extremely difficult, the momentum and enthalpy fluxes were deduced via absolute angular momentum and total energy budgets. An error analysis of the methodology was performed to quantify and mitigate potentially significant uncertainties resulting from unresolved budget terms and observational errors. An analysis of six missions from the 2003 Coupled Boundary Layers Air–Sea Transfer (CBLAST) field program in Major Hurricanes Fabian and Isabel was conducted using a new variational technique. The analysis indicates a near-surface mean drag coefficient CD of 2.4 × 10−3 with a 46% standard deviation and a mean enthalpy coefficient CK of 1.0 × 1...
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Air–Sea Enthalpy and Momentum Exchange at Major Hurricane Wind Speeds Observed during CBLAST
Journal of the Atmospheric Sciences, 2012Co-Authors: Michael M Bell, Michael T Montgomery, Kerry A EmanuelAbstract:AbstractQuantifying air–sea exchanges of enthalpy and momentum is important for understanding and skillfully predicting tropical cyclone intensity, but the magnitude of the corresponding wind speed–dependent bulk exchange coefficients is largely unknown at Major Hurricane wind speeds greater than 50 m s−1. Since direct turbulent flux measurements in these conditions are extremely difficult, the momentum and enthalpy fluxes were deduced via absolute angular momentum and total energy budgets. An error analysis of the methodology was performed to quantify and mitigate potentially significant uncertainties resulting from unresolved budget terms and observational errors. An analysis of six missions from the 2003 Coupled Boundary Layers Air–Sea Transfer (CBLAST) field program in Major Hurricanes Fabian and Isabel was conducted using a new variational technique. The analysis indicates a near-surface mean drag coefficient CD of 2.4 × 10−3 with a 46% standard deviation and a mean enthalpy coefficient CK of 1.0 × 1...
Michael M Bell - One of the best experts on this subject based on the ideXlab platform.
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air sea enthalpy and momentum exchange at Major Hurricane wind speeds observed during cblast
Journal of the Atmospheric Sciences, 2012Co-Authors: Michael M Bell, Michael T Montgomery, Kerry A EmanuelAbstract:AbstractQuantifying air–sea exchanges of enthalpy and momentum is important for understanding and skillfully predicting tropical cyclone intensity, but the magnitude of the corresponding wind speed–dependent bulk exchange coefficients is largely unknown at Major Hurricane wind speeds greater than 50 m s−1. Since direct turbulent flux measurements in these conditions are extremely difficult, the momentum and enthalpy fluxes were deduced via absolute angular momentum and total energy budgets. An error analysis of the methodology was performed to quantify and mitigate potentially significant uncertainties resulting from unresolved budget terms and observational errors. An analysis of six missions from the 2003 Coupled Boundary Layers Air–Sea Transfer (CBLAST) field program in Major Hurricanes Fabian and Isabel was conducted using a new variational technique. The analysis indicates a near-surface mean drag coefficient CD of 2.4 × 10−3 with a 46% standard deviation and a mean enthalpy coefficient CK of 1.0 × 1...
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Air–Sea Enthalpy and Momentum Exchange at Major Hurricane Wind Speeds Observed during CBLAST
Journal of the Atmospheric Sciences, 2012Co-Authors: Michael M Bell, Michael T Montgomery, Kerry A EmanuelAbstract:AbstractQuantifying air–sea exchanges of enthalpy and momentum is important for understanding and skillfully predicting tropical cyclone intensity, but the magnitude of the corresponding wind speed–dependent bulk exchange coefficients is largely unknown at Major Hurricane wind speeds greater than 50 m s−1. Since direct turbulent flux measurements in these conditions are extremely difficult, the momentum and enthalpy fluxes were deduced via absolute angular momentum and total energy budgets. An error analysis of the methodology was performed to quantify and mitigate potentially significant uncertainties resulting from unresolved budget terms and observational errors. An analysis of six missions from the 2003 Coupled Boundary Layers Air–Sea Transfer (CBLAST) field program in Major Hurricanes Fabian and Isabel was conducted using a new variational technique. The analysis indicates a near-surface mean drag coefficient CD of 2.4 × 10−3 with a 46% standard deviation and a mean enthalpy coefficient CK of 1.0 × 1...
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air sea enthalpy and momentum exchange at Major Hurricane wind speeds
18th Conference on Atmospheric BioGeosciences 28th Conference on Agricultural and Forest Meteorology 28th Conference on Hurricanes and Tropical Meteor, 2010Co-Authors: Michael M BellAbstract:Abstract : Air-sea exchanges of heat and momentum are important elements in understanding and skillfully predicting tropical cyclone intensity, but the magnitude of the corresponding wind-speed dependent bulk exchange coefficients is largely unknown at Major Hurricane wind speeds greater than 50 m s-1. Since direct turbulent flux measurements in these conditions are extremely difficult, the momentum and enthalpy fluxes were alternatively deduced via axisymmetric angular momentum and total energy budgets. A comprehensive error analysis was performed using both idealized numerical simulations to quantify and mitigate potentially significant uncertainties resulting from unresolved budget terms and observational errors. An analysis of six missions from the 2003 CBLAST field program in Major Hurricanes Fabian and Isabel was conducted using a new variational technique. This analysis indicates a near-surface mean drag coefficient (CD) of 2.4x10-3 with a 46% standard deviation and a mean enthalpy coefficient (CK) of 1.0x10-3 with a 40% standard deviation for wind speeds between 52 and 72 m s- 1. These are the first known estimates of CK and the ratio of enthalpy to drag coefficient (CK/CD) in Major Hurricanes. The results suggest that there is no significant change in the magnitude of the bulk exchange coefficients estimated at minimal Hurricane wind speeds, and the ratio CK/CD is likely less than 0.75 for wind speeds greater than 50 m s-1.
Michael T Montgomery - One of the best experts on this subject based on the ideXlab platform.
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the azimuthally averaged boundary layer structure of a numerically simulated Major Hurricane
Journal of Advances in Modeling Earth Systems, 2015Co-Authors: Sergio F Abarca, Michael T Montgomery, James C McwilliamsAbstract:This work examines the azimuthally averaged boundary layer structure of a numerically simulated Hurricane. We nominally define the Hurricane boundary layer as the layer in which the effects of surface friction are associated with significant departures from gradient wind balance. The boundary layer in the intensifying primary and forming secondary eyewalls is found to be nonlinear. At large radii, exterior to the eyewalls, Ekman-like balance as traditionally defined, is found to hold true. Where significant departures from Ekman-like balance are found, the departures are characterized by large vertical advection of horizontal velocity through the depth of the boundary layer. Shock-like structures are not found to be prominent in the azimuthally averaged view of the vortex boundary layer, with the largest azimuthally averaged radial gradients of the radial and tangential velocities being on the order of only a few meters per second per kilometer. Also, in the radial regions of the eyewalls, at the height where the averaged tangential wind is a maximum, the radial advection of radial velocity is an order of magnitude smaller than the agradient force per unit mass. Some physical implications of these findings are discussed.
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air sea enthalpy and momentum exchange at Major Hurricane wind speeds observed during cblast
Journal of the Atmospheric Sciences, 2012Co-Authors: Michael M Bell, Michael T Montgomery, Kerry A EmanuelAbstract:AbstractQuantifying air–sea exchanges of enthalpy and momentum is important for understanding and skillfully predicting tropical cyclone intensity, but the magnitude of the corresponding wind speed–dependent bulk exchange coefficients is largely unknown at Major Hurricane wind speeds greater than 50 m s−1. Since direct turbulent flux measurements in these conditions are extremely difficult, the momentum and enthalpy fluxes were deduced via absolute angular momentum and total energy budgets. An error analysis of the methodology was performed to quantify and mitigate potentially significant uncertainties resulting from unresolved budget terms and observational errors. An analysis of six missions from the 2003 Coupled Boundary Layers Air–Sea Transfer (CBLAST) field program in Major Hurricanes Fabian and Isabel was conducted using a new variational technique. The analysis indicates a near-surface mean drag coefficient CD of 2.4 × 10−3 with a 46% standard deviation and a mean enthalpy coefficient CK of 1.0 × 1...
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Air–Sea Enthalpy and Momentum Exchange at Major Hurricane Wind Speeds Observed during CBLAST
Journal of the Atmospheric Sciences, 2012Co-Authors: Michael M Bell, Michael T Montgomery, Kerry A EmanuelAbstract:AbstractQuantifying air–sea exchanges of enthalpy and momentum is important for understanding and skillfully predicting tropical cyclone intensity, but the magnitude of the corresponding wind speed–dependent bulk exchange coefficients is largely unknown at Major Hurricane wind speeds greater than 50 m s−1. Since direct turbulent flux measurements in these conditions are extremely difficult, the momentum and enthalpy fluxes were deduced via absolute angular momentum and total energy budgets. An error analysis of the methodology was performed to quantify and mitigate potentially significant uncertainties resulting from unresolved budget terms and observational errors. An analysis of six missions from the 2003 Coupled Boundary Layers Air–Sea Transfer (CBLAST) field program in Major Hurricanes Fabian and Isabel was conducted using a new variational technique. The analysis indicates a near-surface mean drag coefficient CD of 2.4 × 10−3 with a 46% standard deviation and a mean enthalpy coefficient CK of 1.0 × 1...
Thomas H Jagger - One of the best experts on this subject based on the ideXlab platform.
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changes in the rates of north atlantic Major Hurricane activity during the 20th century
Geophysical Research Letters, 2000Co-Authors: James B Elsner, Thomas H JaggerAbstract:The authors document and explain changes in the rates of North Atlantic Major Hurricanes over the 20th century. A change-point analyses identifies two contrasting regimes of activity. The regimes have significantly different occurrence rates that coincide with changes in the climate over the extratropical North Atlantic. In conjunction with the recent Arctic warming and a relaxation of the North Atlantic oscillation, it is speculated that we are beginning a new period of greater Major Hurricane activity.
