North Atlantic coastal lagoons: conservation, management and research challenges in the twenty-first century

Hydrobiologia ◽  
2012 ◽  
Vol 701 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Nicola A. Beer ◽  
Chris B. Joyce
Keyword(s):  
North Atlantic ◽  
Conservation Management ◽  
Coastal Lagoons ◽  
First Century ◽  
Research Challenges ◽  
Twenty First Century ◽  
Atlantic Coastal

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 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.

scholarly journals Ocean Warming Effect on Surface Gravity Wave Climate Change for the End of the Twenty-First Century

2013 ◽  
Vol 26 (16) ◽  
pp. 6046-6066 ◽  
Author(s):  
Yalin Fan ◽  
Isaac M. Held ◽  
Shian-Jiann Lin ◽  
Xiaolan L. Wang
Keyword(s):  
Climate Change ◽  
North Atlantic ◽  
Austral Summer ◽  
South Pacific ◽  
First Century ◽  
The South ◽  
Coupled Models ◽  
The North ◽  
The North Atlantic ◽  
Twenty First Century

Abstract Surface wind (U10) and significant wave height (Hs) response to global warming are investigated using a coupled atmosphere–wave model by perturbing the sea surface temperatures (SSTs) with anomalies generated by the Working Group on Coupled Modeling (WGCM) phase 3 of the Coupled Model Intercomparison Project (CMIP3) coupled models that use the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4)/Special Report on Emissions Scenarios A1B (SRES A1B) scenario late in the twenty-first century. Several consistent changes were observed across all four realizations for the seasonal means: robust increase of U10 and Hs in the Southern Ocean for both the austral summer and winter due to the poleward shift of the jet stream; a dipole pattern of the U10 and Hs with increases in the northeast sector and decreases at the midlatitude during boreal winter in the North Atlantic due to the more frequent occurrence of the positive phases of the North Atlantic Oscillation (NAO); and strong decrease of U10 and Hs in the tropical western Pacific Ocean during austral summer, which might be caused by the joint effect of the weakening of the Walker circulation and the large hurricane frequency decrease in the South Pacific. Changes of the 99th percentile U10 and Hs are twice as strong as changes in the seasonal means, and the maximum changes are mainly dominated by the changes in hurricanes. Robust strong decreases of U10 and Hs in the South Pacific are obtained because of the large hurricane frequency decrease, while the results in the Northern Hemisphere basins differ among the models. An additional sensitivity experiment suggests that the qualitative response of U10 and Hs is not affected by using SST anomalies only and maintaining the radiative forcing unchanged (using 1980 values), as in this study.

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 Model Projections of the Changes in Atmospheric Circulation and Surface Climate over North America, the North Atlantic, and Europe in the Twenty-First Century

2013 ◽  
Vol 26 (23) ◽  
pp. 9603-9620 ◽  
Author(s):  
Ngar-Cheung Lau ◽  
Jeffrey J. Ploshay
Keyword(s):  
Climate Change ◽  
North America ◽  
North Atlantic ◽  
Storm Track ◽  
First Century ◽  
The North ◽  
Sst Forcing ◽  
The North Atlantic ◽  
Twenty First Century ◽  
North America North

The impacts of climate change on the North America–North Atlantic–Europe sector are studied using a coupled general circulation model: the Climate Model, version 3 (CM3) and a high-resolution atmosphere-only model, the High Resolution Atmospheric Model (HiRAM)—both developed at the Geophysical Fluid Dynamics Laboratory. The CM3 experiment is conducted under two climate change scenarios for the 1860–2100 period. The sea surface temperature (SST) forcing prescribed in the “time slice” integrations with HiRAM is derived from observations for the 1979–2008 period and projection by CM3 for the 2086–95 period. The wintertime response in the late twenty-first century is characterized by an enhancement of the positive phase of the North Atlantic Oscillation in sea level pressure (SLP) and poleward and eastward displacements of the Atlantic jet stream and storm track. The forcing pattern due to eddy vorticity fluxes in the perturbed storm track matches well with the response pattern of the SLP field in the late twenty-first century. The model results suggest that the above circulation changes are linked to the gradient of the altered SST forcing in the North Atlantic. In summer, the projected enhancement of convection over the eastern tropical Pacific is accompanied by a wave train spanning the North America–North Atlantic–Europe sector. This quasi-stationary circulation pattern is associated with diminished storm track activity at 40°–50°N and an eddy forcing pattern similar to the summertime SLP response in the late twenty-first century.

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.

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