scholarly journals Exploring Controls on Tropical Cyclone Count through the Geography of Environmental Favorability

2020 ◽  
Vol 33 (5) ◽  
pp. 1725-1745 ◽  
Author(s):  
Kimberly A. Hoogewind ◽  
Daniel R. Chavas ◽  
Benjamin A. Schenkel ◽  
Morgan E O’Neill
Keyword(s):  
Packing Density ◽  
Seasonal Cycle ◽  
Large Scale ◽  
Separation Distance ◽  
The North ◽  
Storm Duration ◽  
Order Of Magnitude ◽  
The Mean ◽  
Positive Correlations ◽  
Northern And Southern Hemispheres

AbstractGlobally, on the order of 100 tropical cyclones (TCs) occur annually, yet the processes that control this number remain unknown. Here we test a simple hypothesis that this number is limited by the geography of thermodynamic environments favorable for TC formation and maintenance. First, climatologies of TC potential intensity and environmental ventilation are created from reanalyses and are used in conjunction with historical TC data to define the spatiotemporal geography of favorable environments. Based on a range of predefined separation distances, the geographic domain of environmental favorability is populated with randomly placed TCs assuming a fixed minimum separation distance to achieve a maximum daily packing density of storms. Inclusion of a fixed storm duration yields an annual “maximum potential genesis” (MPG) rate, which is found to be an order of magnitude larger than the observed rate on Earth. The mean daily packing density captures the seasonal cycle reasonably well for both the Northern and Southern Hemispheres, though it substantially overestimates TC counts outside of each hemisphere’s active seasons. Interannual variability in MPG is relatively small and is poorly correlated with annual storm count globally and across basins, though modest positive correlations are found in the North Atlantic and east Pacific basins. Overall, the spatiotemporal distribution of favorable environmental conditions appears to strongly modulate the seasonal cycle of TCs, which certainly strongly influences the TC climatology, though it does not explicitly constrain the global annual TC count. Our methodology provides the first estimate of an upper bound for annual TC frequency and outlines a framework for assessing how local and large-scale factors may act to limit global TC count below the maximum potential values found here.

scholarly journals Simulated Relationships between Regional Temperatures and Large-Scale Circulation: 125 kyr BP (Eemian) and the Preindustrial Period

2005 ◽  
Vol 18 (19) ◽  
pp. 4032-4045 ◽  
Author(s):  
Nikolaus Groll ◽  
Martin Widmann ◽  
Julie M. Jones ◽  
Frank Kaspar ◽  
Stephan J. Lorenz
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
Temperature Sensitive ◽  
Proxy Data ◽  
Large Scale Circulation ◽  
The North ◽  
Temperature Signal ◽  
Northern Winter ◽  
The Mean ◽  
Mean Circulation

Abstract To investigate relationships between large-scale circulation and regional-scale temperatures during the last (Eemian) interglacial, a simulation with a general circulation model (GCM) under orbital forcing conditions of 125 kyr BP is compared with a simulation forced with the Late Holocene preindustrial conditions. Consistent with previous GCM simulations for the Eemian, higher northern summer 2-m temperatures are found, which are directly related to the different insolation. Differences in the mean circulation are evident such as, for instance, stronger northern winter westerlies toward Europe, which are associated with warmer temperatures in central and northeastern Europe in the Eemian simulation, while the circulation variability, analyzed by means of a principal component analysis of the sea level pressure (SLP) field, is very similar in both periods. As a consequence of the differences in the mean circulation the simulated Arctic Oscillation (AO) temperature signal in the northern winter, on interannual-to-multidecadal time scales, is weaker during the Eemian than today over large parts of the Northern Hemisphere. Correlations between the AO index and the central European temperature (CET) decrease by about 0.2. The winter and spring SLP anomalies over the North Atlantic/European domain that are most strongly linearly linked to the CET cover a smaller area and are shifted westward over the North Atlantic during the Eemian. However, the strength of the connection between CET and these SLP anomalies is similar in both simulations. The simulated differences in the AO temperature signal and in the SLP anomaly, which is linearly linked to the CET, suggest that during the Eemian the link between the large-scale circulation and temperature-sensitive proxy data from Europe may differ from present-day conditions and that this difference should be taken into account when inferring large-scale climate from temperature-sensitive proxy data.

scholarly journals North-south asynchrony and long-term variations of sunspot latitudes

2008 ◽  
Vol 4 (S259) ◽  
pp. 237-238 ◽  
Author(s):  
Nadezhda V. Zolotova ◽  
D. I. Ponyavin
Keyword(s):  
Sunspot Area ◽  
Magnetic Equator ◽  
Phase Component ◽  
Long Period ◽  
The North ◽  
Sign Change ◽  
The Mean ◽  
South Asymmetry ◽  
Northern And Southern Hemispheres

AbstractThe long-term records of sunspot area available separately for Northern and Southern Hemispheres have been investigated by means of cross-recurrence technique. Phase component of the north-south asymmetry was extracted. This measure demonstrates long-period systematic variations with the sign change of hemispheric leading in 1930s and 1960s. Moreover phase north-south asynchrony anticorrelates with the so called magnetic equator, which was defined as difference of the mean sunspot latitudes between two hemispheres. Relationships of the phase north-south asynchrony, magnetic equator and butterfly diagrams are presented and discussed.

scholarly journals All hands on deck: Large-scale (re)sculpting of cortical circuits in post-resection children

2020 ◽  
Author(s):  
Anne Margarette S. Maallo ◽  
Michael C. Granovetter ◽  
Erez Freud ◽  
Sabine Kastner ◽  
Mark A. Pinsk ◽  
...  
Keyword(s):  
Large Scale ◽  
Brain Regions ◽  
Cortical Circuits ◽  
Pharmacoresistant Epilepsy ◽  
Cortical Volume ◽  
Normal Behavior ◽  
Hands On ◽  
The Mean ◽  
Time Courses ◽  
Positive Correlations

AbstractDespite the relative successes in the surgical treatment of pharmacoresistant epilepsy, there is rather little research on the neural (re)organization that potentially subserves behavioral compensation. Here, we examined the post-surgical functional connectivity (FC) in children and adolescents who have undergone unilateral cortical resection and, yet, display remarkably normal behavior. Conventionally, FC has been investigated in terms of the mean correlation of the BOLD time courses extracted from different brain regions. Here, we demonstrated the value of segregating the voxel-wise relationships into mutually exclusive populations that were either positively or negatively correlated. While, relative to controls, the positive correlations were largely normal, negative correlations among networks were increased. Together, our results point to reorganization in the contralesional hemisphere, possibly suggesting competition for cortical territory due to the demand for representation of function. Conceivably, the ubiquitous negative correlations enable the differentiation of function in the reduced cortical volume following a unilateral resection.

scholarly journals RATE OF GENE SILENCING AT DUPLICATE LOCI: A THEORETICAL STUDY AND INTERPRETATION OF DATA FROM TETRAPLOID FISHES

Genetics ◽  
1980 ◽  
Vol 95 (1) ◽  
pp. 237-258 ◽  
Author(s):  
Wen-Hsiung Li
Keyword(s):  
Large Scale ◽  
Null Allele ◽  
Gene Loss ◽  
Extinction Time ◽  
Effective Population ◽  
Tight Linkage ◽  
Order Of Magnitude ◽  
The Mean ◽  
Duplicate Loci ◽  
Sheltering Effect

ABSTRACT A large-scale simulation has been conducted on the rate of gene loss at duplicate loci under irreversible mutation. It is found that tight linkage does not provide a strong sheltering effect, as thought by previous authors; indeed, the mean loss time for the case of tight linkage is of the same order of magnitude as that for no linkage, as long as Nu is not much larger than 1, where N is the effective population size and u the mutation rate. When Nu is 0.01 or less, the two loci behave almost as neutral loci, regardless of linkage, and the mean loss time is about only half the mean extinction time for a neutral allele under irreversible mutation. However, the former becomes two or more times larger than the latter when Nu ≥ 1.—In the simulation, the sojourn times in the frequency intervals (0, 001) and (0.99, 1) and the time for the frequency of the null allele to reach 0.99 at one of the two loci have also been recorded. The results show that the populatian is monomorphic for the normal allele most of the time if Nu ≤ 0.01, but polymorphic for the null and the normal alleles most of the time if Nu ≥ 0.1.—The distribution of the frequency of the null allele in an equilibrium tetraploid population has been studied analytically. The present results have been applied to interpret data from some fish groups that are of tetraploid origin, and a model for explaining the slow rate of gene loss in these fishes is proposed.

scholarly journals A Diagnosis of Thickness Fluxes in an Eddy-Resolving Model

2007 ◽  
Vol 37 (3) ◽  
pp. 727-742 ◽  
Author(s):  
Carsten Eden ◽  
Richard J. Greatbatch ◽  
Jürgen Willebrand
Keyword(s):  
Large Scale ◽  
North Atlantic Ocean ◽  
A Priori ◽  
Baroclinic Instability ◽  
Optimization Technique ◽  
Subtropical Gyre ◽  
Equatorial Atlantic ◽  
The North ◽  
Eddy Fluxes ◽  
The Mean

Abstract Output from an eddy-resolving model of the North Atlantic Ocean is used to estimate values for the thickness diffusivity κ appropriate to the Gent and McWilliams parameterization. The effect of different choices of rotational eddy fluxes on the estimated κ is discussed. Using the raw fluxes (no rotational flux removed), large negative values (exceeding −5000 m2 s−1) of κ are diagnosed locally, particularly in the Gulf Stream region and in the equatorial Atlantic. Removing a rotational flux based either on the suggestion of Marshall and Shutts or the more general theory of Medvedev and Greatbatch leads to a reduction of the negative values, but they are still present. The regions where κ < 0 correspond to regions where eddies are acting to increase, rather than decrease (as in baroclinic instability) the mean available potential energy. In the subtropical gyre, κ ranges between 500 and 2000 m2 s−1, rapidly decreasing to zero below the thermocline in all cases. Rotational fluxes and κ are also estimated using an optimization technique. In this case, |κ| can be reduced or increased by construction, but the regions where κ < 0 are still present and the optimized rotational fluxes also remain similar to a priori values given by the theoretical considerations. A previously neglected component (ν) of the bolus velocity is associated with the horizontal flux of buoyancy along, rather than across, the mean buoyancy contours. The ν component of the bolus velocity is interpreted as a streamfunction for eddy-induced advection, rather than diffusion, of mean isopycnal layer thickness, showing up when the lateral eddy fluxes cannot be described by isotropic diffusion only. All estimates show a similar large-scale pattern for ν, implying westward advection of isopycnal thickness over much of the subtropical gyre. Comparing ν with a mean streamfunction shows that it is about 10% of the mean in midlatitudes and even larger than the mean in the Tropics.

scholarly journals The Production and Dissipation of Compensated Thermohaline Variance by Mesoscale Stirring

2009 ◽  
Vol 39 (10) ◽  
pp. 2477-2501 ◽  
Author(s):  
K. Shafer Smith ◽  
Raffaele Ferrari
Keyword(s):  
Large Scale ◽  
Vertical Mixing ◽  
Small Scale ◽  
Vertical Diffusion ◽  
The North ◽  
Salinity Gradients ◽  
Scale Temperature ◽  
The Mean ◽  
Geostrophic Turbulence ◽  
Quasigeostrophic Model

Abstract Temperature–salinity profiles from the region studied in the North Atlantic Tracer Release Experiment (NATRE) show large isopycnal excursions at depths just below the thermocline. It is proposed here that these thermohaline filaments result from the mesoscale stirring of large-scale temperature and salinity gradients by geostrophic turbulence, resulting in a direct cascade of thermohaline variance to small scales. This hypothesis is investigated as follows: Measurements from NATRE are used to generate mean temperature, salinity, and shear profiles. The mean stratification and shear are used as the background state in a high-resolution horizontally homogeneous quasigeostrophic model. The mean state is baroclinically unstable, and the model produces a vigorous eddy field. Temperature and salinity are stirred laterally in each density layer by the geostrophic velocity and vertical advection is by the ageostrophic velocity. The simulated temperature–salinity diagram exhibits fluctuations at depths just below the thermocline of similar magnitude to those found in the NATRE data. It is shown that vertical diffusion is sufficient to absorb the laterally driven cascade of tracer variance through an amplification of filamentary slopes by small-scale shear. These results suggest that there is a strong coupling between vertical mixing and horizontal stirring in the ocean at scales below the deformation radius.

Investigation on Dioxin Level of Flue Gas, Ambient Air, Vegetation and Soil Nearby Large-Scale MSWI in Taiwan

2013 ◽  
Vol 781-784 ◽  
pp. 2508-2516
Author(s):  
Yan Hua Wang ◽  
Gui Wei Rao ◽  
Mei Lan Chen ◽  
Jian Yuan Yu ◽  
Guo Ping Chang-Chien
Keyword(s):  
Flue Gas ◽  
Large Scale ◽  
Ambient Air ◽  
Polychlorinated Dibenzofurans ◽  
The North ◽  
Four Seasons ◽  
Dioxin Level ◽  
Emission Limit ◽  
The Mean ◽  
Set Up

We set up information about Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) level in flue gas, ambient air, banyan leaves and soil nearby Muzha MSWI, located in the north of Taiwan. Total PCDD/F I-TEQ concentrations in flue gas are 0.0995, 0.0711ng I-TEQ/Nm3, respectively, in spring, autumn, all below the emission limit regulated by Taiwan EPA, 0.1ng I-TEQ/Nm3 . The mean PCDD/F concentrations in ambient air nearby Muzha MSWIs are 0.0283, 0.0357, 0.0391 and 0.05638pg I-TEQ/Nm3, respectively at four seasons. The mean PCDD/F concentrations in banyan leaves nearby are 3.86, 0.873ng I-TEQ/kg, respectively in spring, autumn. The mean PCDD/F concentrations in soil nearby are 1.733, 2.061ng I-TEQ/kg, respectively in spring, autumn, much lower than the emission limit in soil regulated by Taiwan EPA, 1000ng I-TEQ/kg. By comparing the PCDD/F concentration of sample at upwind and downwind sampling sites, the PCDD/F influence from Muzha MSWI on nearby ambient air, vegetation and soil is not obvious.

Course, Management and Outcome of Oral-Anticoagulant-Related Intracranial Haemorrhages

2000 ◽  
Vol 45 (4) ◽  
pp. 105-109 ◽  
Author(s):  
J. Berwaerts ◽  
O. J. Robb ◽  
R. S. Dykhuizen ◽  
J. Webster
Keyword(s):  
Oral Anticoagulant ◽  
Large Scale ◽  
Tertiary Care ◽  
Tertiary Care Centre ◽  
Term Outcome ◽  
The North ◽  
Significant Difference ◽  
Anticoagulant Reversal ◽  
Mean Size ◽  
The Mean

The aim of this study was to compare the clinical course and radiological features of oral anticoagulant (OAC)-related intracranial haemorrhages with those of haemorrhages unrelated to OAC use admitted over the last six years to a tertiary care centre in the North of Scotland. We furthermore wished to determine the measures taken for reversal of OAC therapy and the resulting short-term outcome. Sixty-eight patients had been treated with OACs at the time of intracranial haemorrhage (32% subdural, 62% intracerebral). Patients admitted with OAC-related and unrelated haemorrhages did not differ significantly in any of the clinical features considered. On CT scan, there was no significant difference according to OAC use in the mean size of subdural (depth 15 ± 5 vs. 18 ±8mm, p=0.36), or intracerebral haematomas (max. diameter 40 ±21 vs. 41 ±20 mm, p=0.73). No reversal measures were taken in 38% of OAC-treated patients. In-hospital mortality was significantly higher for OAC-related haemorrhages compared to unrelated haemorrhages (38% vs. 18%), p=0.001). To further elucidate the effects of anticoagulant reversal on the outcome of OAC-related intracranial haemorrhages, a large-scale prospective study is warranted.

scholarly journals Geochemical evaluation of land use at a medieval harbor site in Masuda City, Chugoku region, Japan

2019 ◽  
pp. 1-13
Author(s):  
Dalai Banzragch ◽  
Hiroaki Ishiga ◽  
Damdinpurev Nasandulam
Keyword(s):  
Large Scale ◽  
Sandy Soils ◽  
Soil Samples ◽  
The North ◽  
Geochemical Evaluation ◽  
Geochemical Variations ◽  
Anthropogenic Processes ◽  
Low Levels ◽  
Positive Correlations ◽  
North And South

A large-scale Medieval harbor site has been recently discovered at Nakazu-Higashihara in Masuda City, Chugoku region, Japan. The Medieval harbor site is divided into north and south areas. The concentration of 22 elements in soil samples from the north of the harbor site was determined in order to identify the geochemical signatures of the Medieval harbor site. The evidence described in the north area is an example of identification of both natural and anthropogenic processes that lead to geochemical variations within the archaeological soils. The north area of the site contains silt and sandy soils characterized by highest concentration of Zr and relatively low levels of most other elements (except for Sr and TS). Negative or weak positive correlations between TiO2 and MnO, and CaO and P2O5 in the north area indicate that this association of elements represents an ancient anthropogenic signature, especially related to residential sites in all soil types. Correlation between TiO2 and Ni, Y, Nb, Zr, Th, and Fe2O3 did not reflect the anthropogenic history. However, these elements and their ratios can be used to identify sources, as well as to establish baseline concentration of other elements which are influenced by anthropogenic and detrital inputs.

scholarly journals Oil Droplet Dispersion under a Deep-Water Plunging Breaker: Experimental Measurement and Numerical Modeling

2020 ◽  
Vol 8 (4) ◽  
pp. 230 ◽  
Author(s):  
Fangda Cui ◽  
Xiaolong Geng ◽  
Brian Robinson ◽  
Thomas King ◽  
Kenneth Lee ◽  
...  
Keyword(s):  
Large Scale ◽  
Droplet Size Distribution ◽  
Breaking Waves ◽  
Droplet Dispersion ◽  
Oil Droplet ◽  
Oil Transport ◽  
Order Of Magnitude ◽  
The Mean ◽  
Spilled Oil ◽  
Plunging Breaker

Knowledge of the droplet size distribution (DSD) of spilled oil is essential for the accurate prediction of oil transport, dissolution, and biodegradation. Breaking waves play important roles in oil droplet formation in oceanic environments. To understand the effects of breaking waves on oil DSD, oil spill experiments were designed and performed in a large-scale wave tank. A plunging breaker with a height of about 0.4 m was produced using the dispersive focusing method within the tank. Oil placed within the breaker resulted in a DSD that was measured using a shadowgraph camera and found to fit a Gaussian distribution N (µ = 1.2 mm, σ2 = 0.29 mm2). For droplets smaller than 1500 µm, the number-based DSD matched the DS1988 correlation, which gives N(d) ~ d−2.3, but this was N(d) ~ d−9.7 for droplets larger than 1500 µm. An order of magnitude investigation revealed that a Gaussian volume-based DSD results in a number-based DSD that may be approximated by d−b (with b ≈ 2) for small diameters (relative to the mean), which explains the occurrence of the DS1988 correlation. With the measured wave hydrodynamics, the VDROP model was adopted to simulate the DSD, which closely matched the observed DSD. The present results reduce the empiricism of the DS1988 correlation.

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