A Simulation Approach for Estimating Hurricane Risk over a 5-yr Horizon

2014 ◽  
Vol 6 (1) ◽  
pp. 77-90 ◽  
Author(s):  
A. Bonazzi ◽  
A. L. Dobbin ◽  
J. K. Turner ◽  
P. S. Wilson ◽  
C. Mitas ◽  
...  
Keyword(s):  
North Atlantic ◽  
Historical Record ◽  
Medium Term ◽  
The Past ◽  
Main Development ◽  
Development Region ◽  
Insurance Perspective ◽  
Hurricane Activity ◽  
Hurricane Track

Abstract We develop a stochastic North Atlantic hurricane track model whose climate inputs are Atlantic main development region (MDR) and Indo-Pacific (IP) sea surface temperatures and produce extremely long model simulations for 58 different climates, each one conditioned on 5 yr of observed SSTs from 1950 to 2011—hereafter referred as medium-term (MT) views. Stringent tests are then performed to prove that MT simulations are better predictors of hurricane landfalls than a long-term view conditioned on the entire SST time series from 1950 to 2011. In this analysis, the authors extrapolate beyond the historical record, but not in terms of a forecast of future conditions. Rather it is attempted to define—within the limitation of the modeling approach—the magnitude of extreme events that could have materialized in the past at fixed probability thresholds and what is the likelihood of observed landfalls given such estimates. Finally, a loss proxy is built and the value of the analysis results from a simplified property and casualty insurance perspective is shown. Medium-term simulations of hurricane activity are used to set the strategy of reinsurance coverage purchased by a hypothetical primary insurance, leading to improved solvency margins.

Impact of Seasonality in the North Atlantic Jet Stream and Storm Migration on the Seasonality of Hurricane Translation Speed Changes

2021 ◽  
pp. 1-38
Author(s):  
Xi Guo ◽  
James P. Kossin ◽  
Zhe-Min Tan
Keyword(s):  
North Atlantic ◽  
Atlantic Coast ◽  
Jet Stream ◽  
Translation Speed ◽  
Multidecadal Variability ◽  
The Past ◽  
The North ◽  
Term Variation ◽  
The North Atlantic

AbstractTropical cyclone (TC) translation speed (TCTS) can affect the duration of TC-related disasters, which is critical to coastal and inland areas. The long-term variation of TCTS and their relationship to the variability of the mid-latitude jet stream and storm migration are discussed here for storms near the North Atlantic coast during 1948-2019. Our results reveal the prominent seasonality in the long-term variation of TCTS, which can be largely explained by the seasonality in the covariations of the mid-latitude jet stream and storm locations. Specifically, significant increases of TCTS occur in June and October during the past decades, which may result from the equatorward displacement of the jet stream and poleward migration of storm locations. Prominent slowdown of TCTS is found in August, which is related to the weakened jet strength and equatorward storm migration. In September, the effects of poleward displacement and weakening of the jet stream on TCTS are largely compensated by the poleward storm migration, therefore, no significant change in TCTS is observed. Meanwhile, the multidecadal variability of the Atlantic may contribute to the multidecadal variability of TCTS. Our findings emphasize the significance in taking a seasonality view in discussing the variability and trends of near-coast Atlantic TCTS under climate change.

Improving Multiseason Forecasts of North Atlantic Hurricane Activity

2008 ◽  
Vol 21 (6) ◽  
pp. 1209-1219 ◽  
Author(s):  
James B. Elsner ◽  
Thomas H. Jagger ◽  
Michael Dickinson ◽  
Dail Rowe
Keyword(s):  
North Atlantic ◽  
Monte Carlo Sampling ◽  
Sea Surface ◽  
Economic Losses ◽  
Atlantic Hurricane ◽  
Time Period ◽  
Hurricane Season ◽  
Hurricane Activity ◽  
Term Management

Abstract Hurricanes cause drastic social problems as well as generate huge economic losses. A reliable forecast of the level of hurricane activity covering the next several seasons has the potential to mitigate against such losses through improvements in preparedness and insurance mechanisms. Here a statistical algorithm is developed to predict North Atlantic hurricane activity out to 5 yr. The algorithm has two components: a time series model to forecast average hurricane-season Atlantic sea surface temperature (SST), and a regression model to forecast the hurricane rate given the predicted SST value. The algorithm uses Monte Carlo sampling to generate distributions for the predicted SST and model coefficients. For a given forecast year, a predicted hurricane count is conditional on a sampled predicted value of Atlantic SST. Thus forecasts are samples of hurricane counts for each future year. Model skill is evaluated over the period 1997–2005 and compared against climatology, persistence, and other multiseasonal forecasts issued during this time period. Results indicate that the algorithm will likely improve on earlier efforts and perhaps carry enough skill to be useful in the long-term management of hurricane risk.

scholarly journals Russian Federation

2019 ◽  
Vol 19 (260) ◽  
Author(s):  
Keyword(s):  
Pension Reform ◽  
Macroeconomic Policy ◽  
Policy Framework ◽  
Structural Constraints ◽  
External Shocks ◽  
Medium Term ◽  
The Past ◽  
Growth Prospects ◽  
Infrastructure Health

In recent years, the authorities have put in place a sound macroeconomic policy framework that has reduced uncertainty and helped weather external shocks. The current macroeconomic policy mix combines moderately tight monetary policy with a broadly neutral fiscal stance. The medium-term growth outlook remains modest due to structural constraints and sanctions. The authorities have implemented some politically difficult measures in the past year (pension reform and a VAT increase) and have announced plans aimed at raising productivity growth, including higher public spending on infrastructure, health, and education. To significantly increase Russia’s long-term growth prospects and reduce stagnation risks, deeper efforts are needed to address the large footprint of the state, overbearing regulation, and governance and institutional weaknesses.

Doha stalemate: The end of trade multilateralism?

2014 ◽  
Vol 41 (2) ◽  
pp. 383-406 ◽  
Author(s):  
VALBONA MUZAKA ◽  
MATTHEW LOUIS BISHOP
Keyword(s):  
Developed Countries ◽  
Medium Term ◽  
Multilateral Trade ◽  
The Past ◽  
Trade Politics ◽  
Recent Trends ◽  
The Developed Countries ◽  
The Many ◽  
Long Term Trend

AbstractThis article challenges conventional narratives that suggest that the travails in the Doha Round, the shift to bilateral free trade agreements, and the broader unfolding of the global crisis collectively presage the decline of either the WTO or the broader institution of multilateral trade. We question the extent to which recent trends can indeed be said to constitute a genuine crisis of trade multilateralism by reflecting upon the contradictory and ambiguous nature of the multilateralism of the past, and also upon how contemporary multilateralism has been framed with reference to it. Our main finding is that, in contrast to the many short and medium-term symptoms which tend to appear in the conventional story of multilateral decline, there is actually a far more worrying long-term trend which underpins the varied conflicts that characterise contemporary trade politics: the fundamental lack of a shared social purpose between the developed countries and the more powerful emerging countries on which a stable, equitable, and legitimate edifice of multilateral trade rules can be erected, institutionalised, and enhanced.

scholarly journals The ability of general circulation models to simulate tropical cyclones and their precursors over the North Atlantic main development region

2012 ◽  
Vol 39 (7-8) ◽  
pp. 1559-1576 ◽  
Author(s):  
Anne Sophie Daloz ◽  
Fabrice Chauvin ◽  
Kevin Walsh ◽  
Sally Lavender ◽  
Deborah Abbs ◽  
...  
Keyword(s):  
Tropical Cyclones ◽  
North Atlantic ◽  
General Circulation ◽  
General Circulation Models ◽  
The North ◽  
Main Development ◽  
Development Region ◽  
The North Atlantic

On vortices initiated over West Africa and their impact on North Atlantic tropical cyclones

2020 ◽  
Author(s):  
Jean Philippe Duvel
Keyword(s):  
West Africa ◽  
North Atlantic ◽  
The North ◽  
Potential Index ◽  
Main Development ◽  
Development Region ◽  
Vertical Development ◽  
Fouta Djallon ◽  
North And South ◽  
Seasonal And Interannual Variations

<p>Numerous low and mid-level vortices are initiated respectively north and south of 15°N in West Africa and enter the North Atlantic where they may trigger cyclogenesis. Applying an objective vortex tracking algorithm on 38 years of meteorological re-analysis, this work investigates the vortex origin and their role in cyclogenesis with an emphasis on: (i) orography, (ii) seasonal variations and, (iii) merge between low and mid-level vortex tracks. North path vortices are mostly initiated downstream of Hoggar Mountains (5°E, 24°N) and south path vortices are mostly initiated downstream of Fouta Djallon Mountains (15°W, 10°N). About 55% of cyclogeneses in the Main Development Region (MDR: east of 60°W; 5 to 20°N) is associated with vortices initiated on the continent east of 10°W. MDR cyclonic activity is governed by seasonal and interannual variations of the local Genesis Potential Index (maximal in August-September) and not by the number of vortices entering the Ocean. North path vortices, which are more numerous in July, are thus less cyclogenetic compared to south path vortices that are more numerous in August-September. Considering together vortices initiated on the continent and near the coast, about 20% of the cyclogeneses are associated with merge of north and south path vortices and about 14% with north path vortices only. The remaining part is mostly associated with south path vortices. In addition, south path vortices with greater intensity and vertical development between Greenwich and the coast are more cyclogenetic.</p>

scholarly journals Long-Term Variability of Temperature and 14C in the Gulf Stream: Oceanographic Implications

Radiocarbon ◽  
1983 ◽  
Vol 25 (2) ◽  
pp. 449-458 ◽  
Author(s):  
Ellen M Druffel
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
Surface Waters ◽  
Gulf Stream ◽  
18Th Century ◽  
Maunder Minimum ◽  
Ice Age ◽  
The Past ◽  
The North

Variability in temperature and 14C levels are recorded in coralline aragonite that grew in the Gulf Stream during the past four centuries. In particular, 18O/16O ratios reflect a decrease of ca 1°C in surface water temperature during the latter part of the Little Ice age. 14C levels also rose in the surface waters of the Gulf Stream and in atmospheric CO2 during the Maunder minimum. These observations indicate that ocean circulation may have been significantly different in the North Atlantic around the beginning of the 18th century.

scholarly journals A century of geometry and velocity evolution at Eqip Sermia, West Greenland

2016 ◽  
Vol 62 (234) ◽  
pp. 640-654 ◽  
Author(s):  
MARTIN P. LÜTHI ◽  
ANDREAS VIELI ◽  
LUC MOREAU ◽  
IAN JOUGHIN ◽  
MORITZ REISSER ◽  
...  
Keyword(s):  
Greenland Ice Sheet ◽  
Historical Record ◽  
Flow Speed ◽  
Past Century ◽  
Dynamic Changes ◽  
West Greenland ◽  
The Past ◽  
Ice Surface

ABSTRACTRapid dynamic changes of ocean-terminating outlet glaciers of the Greenland ice sheet are related to atmospheric and oceanic warming but the detailed link to external forcing is not well understood. Observations show high variability in dynamic changes and are mainly limited to the past three decades with dense satellite observations. Here we compile a long-term record of dynamic changes of Eqip Sermia Glacier, West Greenland. Starting in 1912, we combine historical measurements of terminus positions, ice-surface elevation and flow velocity together with more recent in-situ and remote-sensing observations. In the 20th century, the glacier underwent small variations in terminus position and flow speed. Between 2000 and 2003, the terminus retreated substantially, but stabilized thereafter. In 2009, the northern terminus lobe started to retreat very rapidly; the southern lobe collapsed in 2013. The present terminus position, which has retreated by 4 km since 1920, is unprecedented in the historical record. Flow velocities were relatively stable until 2010. The recent acceleration reached threefold velocities in 2014 and rapidly affected the whole terminus region up to 15 km inland. Comparison with forcings from the atmosphere and the ocean over the past century shows that no dominant cause can be identified, and that local effects of bed geometry modulate the glacier response.

scholarly journals The response of diatom assemblages in a Jamaican coastal lagoon to hurricane and drought activity over the past millennium

The Holocene ◽  
2021 ◽  
pp. 095968362110190
Author(s):  
Charlotte A Heller ◽  
Neal Michelutti ◽  
Michael J Burn ◽  
Suzanne E Palmer ◽  
John P Smol
Keyword(s):  
Coastal Lagoon ◽  
Lake Level ◽  
Rainfall Variability ◽  
Diatom Assemblages ◽  
Chl A ◽  
Lake Level Changes ◽  
The Past ◽  
Hurricane Activity ◽  
Past Millennium

Reconstructing pre-industrial hurricane activity and aridity from natural archives places modern trends within the context of long-term natural variability. The first reconstruction of Atlantic hurricane activity in Jamaica was based on a sediment record previously obtained from a coastal lagoon. Specifically, an Extended Hurricane Activity (EHA) index was developed from high-resolution geochemical data that linked fluctuations in lake-level changes to rainfall variability associated with hurricane activity. Here, we analyse the same sediment core from which the EHA index was developed to assess the response of biological indicators, namely fossil diatom assemblages and sediment chlorophyll a (chl- a) concentrations, to hydrometeorological events (tropical cyclone-induced precipitation and droughts) over the past ~1500 years. The diatom assemblages responded sensitively to changes in salinity associated with lake-level changes driven by the balance of precipitation and evaporation. Aquatic production (inferred from sediment chl- a, which includes its main diagenetic products) and salinity (inferred from ITRAXTM µXRF chlorine counts) vary inversely following ca. 1300 CE, likely due to enhanced nutrient delivery from freshwater runoff during periods of elevated precipitation. Although the temporal resolution of our biological data is less-well resolved than that of the geochemical record, it generally tracks long-term trends in rainfall variability inferred by the EHA index over the past millennium. This further demonstrates the potential of using biological proxies from coastal lagoons to track past hurricane activity and aridity.

scholarly journals An Objective Satellite-Based Tropical Cyclone Size Climatology

2014 ◽  
Vol 27 (1) ◽  
pp. 455-476 ◽  
Author(s):  
John A. Knaff ◽  
Scott P. Longmore ◽  
Debra A. Molenar
Keyword(s):  
North Atlantic ◽  
North Pacific ◽  
Historical Record ◽  
Maximum Intensity ◽  
Low Level ◽  
The North ◽  
Tangential Wind ◽  
Long Term Trends ◽  
The Individual

Abstract Storm-centered infrared (IR) imagery of tropical cyclones (TCs) is related to the 850-hPa mean tangential wind at a radius of 500 km (V500) calculated from 6-hourly global numerical analyses for North Atlantic and eastern North Pacific TCs for 1995–2011. V500 estimates are scaled using the climatological vortex decay rate beyond 500 km to estimate the radius of 5 kt (1 kt = 0.514 m s−1) winds (R5) or TC size. A much larger historical record of TC-centered IR imagery (1978–2011) is then used to estimate TC sizes and form a global TC size climatology. The basin-specific distributions of TC size reveal that, among other things, the eastern North Pacific TC basins have the smallest while western North Pacific have the largest TC size distributions. The life cycle of TC sizes with respect to maximum intensity shows that TC growth characteristics are different among the individual TC basins, with the North Atlantic composites showing continued growth after maximum intensity. Small TCs are generally located at lower latitudes, westward steering, and preferred in seasons when environmental low-level vorticity is suppressed. Large TCs are generally located at higher latitudes, poleward steering, and preferred in enhanced low-level vorticity environments. Postmaximum intensity growth of TCs occurs in regions associated with enhanced baroclinicity and TC recurvature, while those that do not grow much are associated with west movement, erratic storm tracks, and landfall at or near the time of maximum intensity. With respect to climate change, no significant long-term trends are found in the dataset of TC size.

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