scholarly journals Application of Artificial Neural Networks on North Atlantic Tropical Cyclogenesis Potential Index in Climate Change

2012 ◽  
Vol 29 (9) ◽  
pp. 1202-1220 ◽  
Author(s):  
Zheng Ki Yip ◽  
M. K. Yau
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Tropical Cyclone ◽  
North Atlantic ◽  
The United States ◽  
First Century ◽  
The North ◽  
Potential Index ◽  
Artificial Neural ◽  
Twenty First Century

Abstract A methodology using artificial neural networks is presented to project twenty-first-century changes in North Atlantic tropical cyclone (TC) genesis potential (GP) in a five-model ensemble of global climate models. Two types of neural networks—the self-organizing maps (SOMs) and the forward-feeding back-propagating neural networks (FBNNs)—were employed. This methodology is demonstrated to be a robust alternative to using GCM output directly for tropical cyclone projections, which generally require high-resolution simulations. By attributing the projected changes to the related environmental variables, Emanuel’s revised genesis potential index is used to measure the GP. Changes are identified in the first (P1) and second (P2) half of the twenty-first century. The early and late summer GP decreases in both the P1 and P2 periods over most of the eastern half of the basin and increases off the East Coast of the United States and the north coast of Venezuela during P1. The peak summer GP over the region of frequent TC genesis is projected to decrease more substantially in P1 than in P2. Vertical wind shear (850–200 hPa), temperature (600 hPa), and potential intensity are the most important controls of TC genesis in the North Atlantic basin (NAB) under the changing climate.

scholarly journals Dynamical Simulations of North Atlantic Tropical Cyclone Activity Using Observed Low-Frequency SST Oscillation Imposed on CMIP5 Model RCP4.5 SST Projections

2014 ◽  
Vol 27 (21) ◽  
pp. 8055-8069 ◽  
Author(s):  
Timothy E. LaRow ◽  
Lydia Stefanova ◽  
Chana Seitz
Keyword(s):  
Tropical Cyclone ◽  
North Atlantic ◽  
Climate Models ◽  
The United States ◽  
Tropical Cyclone Activity ◽  
First Century ◽  
Cyclone Activity ◽  
The Mean ◽  
Twenty First Century ◽  
Atlantic Tropical Cyclone

Abstract The effects on early and late twenty-first-century North Atlantic tropical cyclone statistics resulting from imposing the patterns of maximum/minimum phases of the observed Atlantic multidecadal oscillation (AMO) onto projected sea surface temperatures (SSTs) from two climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) are examined using a 100-km resolution global atmospheric model. By imposing the observed maximum positive and negative phases of the AMO onto two CMIP5 SST projections from the representative concentration pathway (RCP) 4.5 scenario, this study places bounds on future North Atlantic tropical cyclone activity during the early (2020–39) and late (2080–99) twenty-first century. Averaging over both time periods and both AMO phases, the mean named tropical cyclones (NTCs) count increases by 35% when compared to simulations using observed SSTs from 1982 to 2009. The positive AMO simulations produce approximately a 68% increase in mean NTC count, while the negative AMO simulations are statistically indistinguishable from the mean NTC count determined from the 1995–2009 simulations—a period of observed positive AMO phase. Examination of the tropical cyclone track densities shows a statistically significant increase in the tracks along the East Coast of the United States in the future simulations compared to the models’ 1982–2009 climate simulations. The increase occurs regardless of AMO phase, although the negative phase produces higher track densities. The maximum wind speeds increase by 6%, in agreement with other climate change studies. Finally, the NTC-related precipitation is found to increase (approximately by 13%) compared to the 1982–2009 simulations.

scholarly journals The Present-Day Simulation and Twenty-First-Century Projection of the Climatology of Extratropical Transition in the North Atlantic

2017 ◽  
Vol 30 (8) ◽  
pp. 2739-2756 ◽  
Author(s):  
Maofeng Liu ◽  
Gabriel A. Vecchi ◽  
James A. Smith ◽  
Hiroyuki Murakami
Keyword(s):  
North Atlantic ◽  
Global Climate Model ◽  
The United States ◽  
First Century ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Extratropical Transition ◽  
The North ◽  
The North Atlantic ◽  
Twenty First Century ◽  
Eastern North Atlantic

This study explores the simulations and twenty-first-century projections of extratropical transition (ET) of tropical cyclones (TCs) in the North Atlantic, with a newly developed global climate model: the Forecast-Oriented Low Ocean Resolution (FLOR) version of the Geophysical Fluid Dynamics Laboratory (GFDL) Coupled Model version 2.5 (CM2.5). FLOR exhibits good skill in simulating present-day ET properties (e.g., cyclone phase space parameters). A version of FLOR in which sea surface temperature (SST) biases are artificially corrected through flux-adjustment (FLOR-FA) shows much improved simulation of ET activity (e.g., annual ET number). This result is largely attributable to better simulation of basinwide TC activity, which is strongly dependent on larger-scale climate simulation. FLOR-FA is also used to explore changes of ET activity in the twenty-first century under the representative concentration pathway (RCP) 4.5 scenario. A contrasting pattern is found in which regional TC density increases in the eastern North Atlantic and decreases in the western North Atlantic, probably due to changes in the TC genesis location. The increasing TC frequency in the eastern Atlantic is dominated by increased ET cases. The increased density of TCs undergoing ET in the eastern subtropics of the Atlantic shows two propagation paths: one moves northwest toward the northeast coast of the United States and the other moves northeast toward western Europe, implying increased TC-related risks in these regions. A more TC-favorable future climate, evident in the projected changes of SST and vertical wind shear, is hypothesized to favor the increased ET occurrence in the eastern North Atlantic.

scholarly journals Atlantic Meridional Overturning Circulation (AMOC) in CMIP5 Models: RCP and Historical Simulations

2013 ◽  
Vol 26 (18) ◽  
pp. 7187-7197 ◽  
Author(s):  
Wei Cheng ◽  
John C. H. Chiang ◽  
Dongxiao Zhang
Keyword(s):  
North Atlantic ◽  
Coupled Model ◽  
Meridional Overturning Circulation ◽  
First Century ◽  
Model Intercomparison ◽  
The North ◽  
Intercomparison Project ◽  
Meridional Overturning ◽  
The North Atlantic ◽  
Twenty First Century

Abstract The Atlantic meridional overturning circulation (AMOC) simulated by 10 models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) for the historical (1850–2005) and future climate is examined. The historical simulations of the AMOC mean state are more closely matched to observations than those of phase 3 of the Coupled Model Intercomparison Project (CMIP3). Similarly to CMIP3, all models predict a weakening of the AMOC in the twenty-first century, though the degree of weakening varies considerably among the models. Under the representative concentration pathway 4.5 (RCP4.5) scenario, the weakening by year 2100 is 5%–40% of the individual model's historical mean state; under RCP8.5, the weakening increases to 15%–60% over the same period. RCP4.5 leads to the stabilization of the AMOC in the second half of the twenty-first century and a slower (then weakening rate) but steady recovery thereafter, while RCP8.5 gives rise to a continuous weakening of the AMOC throughout the twenty-first century. In the CMIP5 historical simulations, all but one model exhibit a weak downward trend [ranging from −0.1 to −1.8 Sverdrup (Sv) century−1; 1 Sv ≡ 106 m3 s−1] over the twentieth century. Additionally, the multimodel ensemble–mean AMOC exhibits multidecadal variability with a ~60-yr periodicity and a peak-to-peak amplitude of ~1 Sv; all individual models project consistently onto this multidecadal mode. This multidecadal variability is significantly correlated with similar variations in the net surface shortwave radiative flux in the North Atlantic and with surface freshwater flux variations in the subpolar latitudes. Potential drivers for the twentieth-century multimodel AMOC variability, including external climate forcing and the North Atlantic Oscillation (NAO), and the implication of these results on the North Atlantic SST variability are discussed.

scholarly journals Artificial Neural Networks for Satellite Image Classification of Shoreline Extraction for Land and Water Classes of the North West Coast of Peninsular Malaysia

2018 ◽  
Vol 24 (2) ◽  
pp. 1382-1387 ◽  
Author(s):  
Syaifulnizam Abd Manaf ◽  
Norwati Mustapha ◽  
Md. Nasir Sulaiman ◽  
Nor Azura Husin ◽  
Mohd Radzi Abdul Hamid
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Image Classification ◽  
West Coast ◽  
Satellite Image ◽  
Peninsular Malaysia ◽  
North West ◽  
The North ◽  
Artificial Neural

Burzum shirts, paramilitarism and National Socialist Black Metal in the twenty-first century

2021 ◽  
Vol 7 (1) ◽  
pp. 27-42 ◽  
Author(s):  
Benjamin Hedge Olson
Keyword(s):  
The United States ◽  
First Century ◽  
Political Life ◽  
Radical Right ◽  
Far Right ◽  
National Socialist ◽  
Black Metal ◽  
The North ◽  
Twenty First Century ◽  
Underground Music

Over the last ten years, the radical right has proliferated at an alarming rate in the United States. National Socialist Black Metal (NSBM) has become an important feature of neo-Nazi, White supremacist and militant racist groups as the radical right as a whole has gained traction in American political life. Although rooted in underground music-based subculture, NSBM has become an important crypto-signifier for the radical right in the twenty-first century providing both symbolic value and ideological inspiration. The anti-racist and apolitical elements of the North American metal scene have responded in a variety of different ways, sometimes challenging racist elements directly, at other times providing ambivalent acceptance of the far right within the scene. While fans, musicians, journalists and record labels struggle to come to terms with the meaning of NSBM and how it should be addressed, NSBM-affiliated political and paramilitary groups have formed and started making their violent fantasies a reality. As many elements within the American metal scene continue to perceive NSBM as a purely artistic movement of no concern to the world outside of the metal scene, proponents of NSBM are marching in the streets of Charlottesville, burning African American churches, murdering LGBTQ people and plotting acts of domestic terrorism.

Winter surface air temperature prediction over Japan using artificial neural networks

2021 ◽  
Author(s):  
J. V. Ratnam ◽  
Masami Nonaka ◽  
Swadhin K. Behera
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
Correlation Coefficients ◽  
Ann Model ◽  
Anomaly Correlation ◽  
The North ◽  
Skill Scores ◽  
Artificial Neural

AbstractThe machine learning technique, namely Artificial Neural Networks (ANN), is used to predict the surface air temperature (SAT) anomalies over Japan in the winter months of December, January and February for the period 1949/50 to 2019/20. The predictions are made for the four regions Hokkaido, North, Central and West of Japan. The inputs to the ANN model are derived from the anomaly correlation coefficients among the SAT anomalies over the regions of Japan and the global SAT and sea surface temperature anomalies. The results are validated using anomaly correlation coefficient (ACC) skill scores with the observation. It is found that the ANN predictions over Hokkaido have higher ACC skill scores compared to the ACC scores over the other three regions. The ANN predicted SAT anomalies are compared with that of ensemble mean of 8 of the North American Multi-Model Ensemble (NMME) models besides comparing them with the persistent anomalies. The ANN predictions over all the four regions have higher ACC skill scores compared to the NMME model skill scores in the common period of 1982/83 to 2018/19. The ANN predicted SAT anomalies also have higher Hit rate and lower False alarm rate compared to the NMME predicted SAT anomalies. All these indicate that the ANN model is a promising tool for predicting the winter SAT anomalies over Japan.

Simulation of the Mean-Zero-Up-Crossing Wave Period Using Artificial Neural Networks Trained With Simulated Annealing Algorithm

2006 ◽  
Author(s):  
H. Bazargan ◽  
H. Bahai ◽  
F. Aryana ◽  
S. F. Yasseri
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Simulated Annealing ◽  
Simulated Annealing Algorithm ◽  
North East ◽  
The North ◽  
Wave Heights ◽  
Significant Wave Heights ◽  
Annealing Algorithm ◽  
Artificial Neural

The aim of this work is to simulate the 3-houly mean zero-up-crossing wave periods (Tzs) of the sea-states of a future period for a location in the North East Pacific. Seven multi-layer artificial neural networks (ANNs) were trained with simulated annealing algorithm. The output of each ANN was used for estimating each of the 7 parameters of a new distribution, described in Appendix A, called hepta-parameter spline proposed for the conditional distribution of the Tz given some significant wave heights and mean zero-up-crossing wave periods. After estimating the parameters of the conditional distributions, the Tzs have been forecasted from the hepta-parameter spline distributions corresponding to the Tzs of the period.

scholarly journals An Analysis of the Effect of Global Warming on the Intensity of Atlantic Hurricanes Using a GCM with Statistical Refinement

2010 ◽  
Vol 23 (23) ◽  
pp. 6382-6393 ◽  
Author(s):  
Ming Zhao ◽  
Isaac M. Held
Keyword(s):  
North Atlantic ◽  
First Century ◽  
Coupled Models ◽  
The North ◽  
Intensity Changes ◽  
Sea Surface Temperature Anomalies ◽  
Sst Warming ◽  
The North Atlantic ◽  
Twenty First Century ◽  
Atlantic Hurricanes

Abstract A statistical intensity adjustment is utilized to extract information from tropical cyclone simulations in a 50-km-resolution global model. A simple adjustment based on the modeled and observed probability distribution of storm lifetime maximum wind speed allows the model to capture the differences between observed intensity distributions in active/inactive year composites from the 1981–2008 period in the North Atlantic. This intensity adjustment is then used to examine the atmospheric model’s responses to different sea surface temperature anomalies generated by coupled models for the late twenty-first century. In the North Atlantic all simulations produce a reduction in the total number of cyclones, but with large intermodel spread in the magnitude of the reduction. The intensity response is positively correlated with changes in frequency across the ensemble. However, there is, on average, an increase in intensity in these simulations despite the mean reduction in frequency. The authors argue that it is useful to decompose these intensity changes into two parts: an increase in intensity that is intrinsic to the climate change experiments and a change in intensity positively correlated with frequency, just as in the active/inactive historical composites. By isolating the intrinsic component, which is relatively independent of the details of the SST warming pattern, an increase is found in storm-lifetime maximum winds of 5–10 m s−1 for storms with intensities of 30–60 m s−1, by the end of the twenty-first century. The effects of change in frequency, which are dependent on the details of the spatial structure of the warming, must then be superimposed on this intrinsic change.

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