scholarly journals Temporal and spatial analysis of ozone concentrations in Europe based on time scale decomposition and a multi-clustering approach

2019 ◽  
Author(s):  
Eirini Boleti ◽  
Christoph Hueglin ◽  
Stuart K. Grange ◽  
André S. H. Prévôt ◽  
Satoshi Takahama
Keyword(s):  
Time Scale ◽  
Seasonal Cycle ◽  
Clustering Algorithm ◽  
Short Term ◽  
Ozone Concentrations ◽  
Time Period ◽  
Term Variation ◽  
Long Term Trends ◽  
Time Scale Decomposition

Abstract. Air quality measures that were implemented in Europe in the 1990s resulted in reductions of ozone precursors concentrations. In this study, the effect of these reductions on ozone is investigated by analyzing surface measurements of ozone for the time period between 2000 and 2015. Using a non-parametric time scale decomposition methodology, the long-term, seasonal and short-term variation of ozone observations were extracted. A clustering algorithm was applied to the different time scale variations, leading to a classification of sites across Europe based on the temporal characteristics of ozone. The clustering based on the long-term variation resulted in a site type classification, while a regional classification was obtained based on the seasonal and short-term variations. Long-term trends of de-seasonalized mean and meteo-adjusted peak ozone concentrations were calculated across large parts of Europe for the time period 2000–2015. A multi-dimensional scheme was used for a detailed trend analysis, based on the identified clusters, which reflect precursor emissions and meteorological influence either on the inter-annual or the short-term time scale. Decreasing mean ozone concentrations at rural sites and increasing or stabilizing at urban sites were observed. At the same time downward trends for peak ozone concentrations were detected for all site types. The effect of hemispheric transport of ozone can be seen either in regions affected by synoptic patterns in the northern Atlantic or at sites located at remote high altitude locations. In addition, a reduction of the amplitude in the seasonal cycle of ozone was observed, and a shift in the occurrence of the seasonal maximum towards earlier time of the year. Finally, a reduced sensitivity of ozone to temperature was identified. It was concluded that long-term trends of mean and peak ozone concentrations are mostly controlled by precursors emissions changes, while seasonal cycle trends and changes in the sensitivity of ozone to temperature are driven by regional climatic conditions.

scholarly journals Temporal and spatial analysis of ozone concentrations in Europe based on timescale decomposition and a multi-clustering approach

2020 ◽  
Vol 20 (14) ◽  
pp. 9051-9066 ◽  
Author(s):  
Eirini Boleti ◽  
Christoph Hueglin ◽  
Stuart K. Grange ◽  
André S. H. Prévôt ◽  
Satoshi Takahama
Keyword(s):  
Seasonal Cycle ◽  
Clustering Algorithm ◽  
Climatic Conditions ◽  
Short Term ◽  
Ozone Concentrations ◽  
Time Period ◽  
Term Variation ◽  
Long Term Trends ◽  
Rural Sites

Abstract. Air quality measures that were implemented in Europe in the 1990s resulted in reductions of ozone precursor concentrations. In this study, the effect of these reductions on ozone is investigated by analyzing surface measurements of this pollutant for the time period between 2000 and 2015. Using a nonparametric timescale decomposition methodology, the long-term, seasonal and short-term variation in ozone observations were extracted. A clustering algorithm was applied to the different timescale variations, leading to a classification of sites across Europe based on the temporal characteristics of ozone. The clustering based on the long-term variation resulted in a site-type classification, while a regional classification was obtained based on the seasonal and short-term variations. Long-term trends of deseasonalized mean and meteo-adjusted peak ozone concentrations were calculated across large parts of Europe for the time period 2000–2015. A multidimensional scheme was used for a detailed trend analysis, based on the identified clusters, which reflect precursor emissions and meteorological influence either on the inter-annual or the short-term timescale. Decreasing mean ozone concentrations at rural sites and increasing or stabilizing at urban sites were observed. At the same time, downward trends for peak ozone concentrations were detected for all site types. In addition, a reduction of the amplitude in the seasonal cycle of ozone and a shift in the occurrence of the seasonal maximum towards earlier time of the year were observed. Finally, a reduced sensitivity of ozone to temperature was identified. It was concluded that long-term trends of mean and peak ozone concentrations are mostly controlled by precursor emissions changes, while seasonal cycle trends and changes in the sensitivity of ozone to temperature are among other factors driven by regional climatic conditions.

Theoretical Aspects of the Rapidly Oscillating AP Stars

1998 ◽  
Vol 11 (2) ◽  
pp. 686-688
Author(s):  
H. Shibahashi
Keyword(s):  
Time Scale ◽  
Short Term ◽  
Pulsating Stars ◽  
Term Variation ◽  
Delta Scuti ◽  
Magnetic Strength ◽  
Ap Stars ◽  
Scuti Stars ◽  
Chemical Peculiarity

Until the rapid oscillations in Przybylski’s star, HD 101065, were discovered by Kurtz in 1978, chemical peculiarity and pulsation were thought to be mutually exclusive. Though the location of the Ap stars in the HR diagram overlaps with that of the Delta Scuti stars, no Ap stars were known to pulsate, and the Delta Scuti type pulsating stars, with a few exceptions, were not claimed to reveal chemical peculiarity. The striking impact of the discovery of the rapid oscillations of Ap stars is that the basic conception of the exclusiveness of the chemical peculiarity and the pulsation was broken. So far, twenty-nine Ap stars have been discovered to be rapidly oscillating Ap (roAp) stars (Kurtz 1997). The observed pulsations of Ap stars are, however, different from those of the Delta Scuti stars in various aspects. The pulsation periods of roAp stars are typically 10.minutes and are much shorter than those of the Delta Scuti stars, which are typically 2 hrs. In some cases, the amplitudes are modulated with the same period and phase as the magnetic strength variation. The amplitudes of some of the roAp stars are very stable, while some others show a fairly short-term variation of a time scale of a day. Some of the roAp stars show a long-term variation of the frequency with a time scale of years.

scholarly journals Spectral UV measurements in Austria from 1994 to 2006: investigations of short- and long-term changes

2008 ◽  
Vol 8 (1) ◽  
pp. 2403-2428
Author(s):  
S. Simic ◽  
P. Weihs ◽  
A. Vacek ◽  
H. Kromp-Kolb ◽  
M. Fitzka
Keyword(s):  
Trend Test ◽  
Atmospheric Variability ◽  
Short Term ◽  
Time Period ◽  
Uv Irradiance ◽  
Long Term Changes ◽  
Long Term Trends ◽  
Short And Long Term ◽  
Double Monochromator

Abstract. Influences of atmospheric variability on short- and long-term changes of spectral UV irradiance measured at the Sonnblick observatory (47.03 N, 12.57 E, 3106 m) during the period from 1994 to 2006 is studied. Measurements are performed with a Brewer ozone single spectrophotometer and with a Bentham DM150 spectroradiometer (double monochromator). The influence of ozone, albedo and clouds on UV variability is evaluated separately using 10-year climatology. It is found that the effect of total ozone on short-term variability of UV irradiance at 305 nm can be more than 200% and on average more than 50%. Clouds can cause variability of 150% or more and on average 35%. Variability caused by albedo is maximum 32%. Long-term trends are investigated for the time period from 1994 to 2006 using the non-parametric Mann-Kendall trend test. Significant downwards trends (99% confidence level) were found for solar zenith angle 55° at wavelengths from 305 nm to 324 nm and CIE.

ON THE CONSUMPTION/DISTRIBUTION THEOREM UNDER THE LONG-RUN GROWTH CRITERION SUBJECT TO A DRAWDOWN CONSTRAINT

2010 ◽  
Vol 13 (06) ◽  
pp. 931-957 ◽  
Author(s):  
MICHAEL J. KLASS ◽  
KRZYSZTOF NOWICKI
Keyword(s):  
Growth Rate ◽  
Short Term ◽  
Long Run ◽  
Time Period ◽  
Total Capital ◽  
Growth Criterion ◽  
Drawdown Constraint ◽  
Riskless Asset ◽  
Distribution Theorem

Consider any discrete time sequence of investment fortunes Fn which has a finite long-run growth rate [Formula: see text] when subject to the present value capital drawdown constraint Fne-rn ≥ λ* max 0≤k≤nFke-rk, where 0 ≤ λ* < 1, in the presence of a riskless asset affording a return of er dollars per time period per dollar invested. We show that money can be withdrawn for consumption from the invested capital without either reducing the long-run growth rate of such capital or violating the drawdown constraint for our capital sequence, while simultaneously increasing the amount of capital withdrawn for consumption at the identical long-term rate of V(r, λ*). We extend this result to an exponentially increasing number of consumption categories and discuss how additional yearly contributions can temporarily augment the total capital under management. In addition, we assess the short-term practicality of creating such an endowment/consumption/distribution program.

scholarly journals COASTAL CHANGES AT BETHANY BEACH, DELAWARE

1984 ◽  
Vol 1 (19) ◽  
pp. 112 ◽  
Author(s):  
Jennifer E. Dick ◽  
Robert A. Dalrymple
Keyword(s):  
Coastal Erosion ◽  
Coastal Processes ◽  
Short Term ◽  
Winter Storms ◽  
Barrier Beach ◽  
Commercial Activities ◽  
Long Term Trends ◽  
Coastal Changes ◽  
Summer Homes

The coastal processes affecting Bethany Beach, Delaware were studied and the short-term and long-term trends in coastal changes were determined in order to develop recommendations for protecting Bethany against coastal erosion (Dick and Dalrymple, 1983). Bethany Beach is located on the Delaware Atlantic coastline which is a wide sandy baymouth barrier beach distinguished by highlands at Rehoboth Beach and Bethany Beach. The shoreline is straight, with only minor bulges and indentations (see Figure 1). Bethany Beach is a residential and resort community. Privatelyowned properties front the publicly-owned beach. Construction of new motels and summer homes is anticipated along with the continued growth of commercial activities to accommodate the increased number of visitors. Bethany is protected by a series of nine groins built between 1934 and 1945. Many of these groins have deteriorated, and are flanked at the landward end. Winter storms severely erode the beach and damage shorefront property. The beach is generally narrow (approximately 45 m wide), especially along the southern portion, and is backed by low dunes (about 15-45 m above NGVD). A timber bulkhead extends along most of the backshore.

scholarly journals Satellites, Self-reports, and Submersion: Exposure to Floods in Bangladesh

2015 ◽  
Vol 105 (5) ◽  
pp. 232-236 ◽  
Author(s):  
Raymond Guiteras ◽  
Amir Jina ◽  
A. Mushfiq Mobarak
Keyword(s):  
Climate Change ◽  
Economic Activity ◽  
Climate Change Impacts ◽  
Objective Data ◽  
Short Term ◽  
Temperature And Precipitation ◽  
Flood Exposure ◽  
Self Reports ◽  
Term Variation

A burgeoning “Climate-Economy” literature has uncovered many effects of changes in temperature and precipitation on economic activity, but has made considerably less progress in modeling the effects of other associated phenomena, like natural disasters. We develop new, objective data on floods, focusing on Bangladesh. We show that rainfall and self-reported exposure are weak proxies for true flood exposure. These data allow us to study adaptation, giving accurate measures of both long-term averages and short term variation in exposure. This is important in studying climate change impacts, as people will not only experience new exposures, but also experience them differently.

The effect of the financing structure on the return on the market share in Saudi companies An Empirical Study: أثر هيكل التمويل على عائد السهم السوقي في الشركات السعودية: دراسة تطبيقية

2020 ◽  
Vol 4 (11) ◽  
Author(s):  
Fatimah Mohammad Asiri
Keyword(s):  
Market Share ◽  
Food Production ◽  
Analytical Approach ◽  
Negative Impact ◽  
Short Term ◽  
Financing Structure ◽  
Time Period ◽  
Comprehensive Survey ◽  
Study Population

The study aimed to identify the influence of the financing structure on the return of the market share in Saudi corporations/companies. The study applied the descriptive-analytical approach, and the study population consisted of some joint-stock companies in the Saudi stock market, where the study sample consisted of (75) companies in five productive sectors where concentration was made on the following sectors: (basic materials, long-term commodities, energy, food production, capital goods). Method of the comprehensive survey was used for all companies. The data was analyzed using the Panel Data method through the STATA program. The study concluded several findings, the most important of which are that short-term debt (liabilities) have a negative impact on the return on the market share, as increasing short debts (liabilities) lead to a decrease in the return on the market share, and that long-term debt (liabilities) have no effect on the return on the market share, and equity has a negative impact on the return on the market share, as the increase in financing through equity leads to a decrease in the return on the market share. The study recommended the necessity of diversification between sources of financing and not limited to debt and long & short-term liabilities only. It also recommended conducting such a study on other sectors or conducting it on the whole market which may result in improving results, and also recommends expanding the time period more than five years, which may lead to improve results.

15. Democracies, Democratization, and Authoritarian Regimes

2020 ◽  
pp. 336-362
Author(s):  
Peter Ferdinand
Keyword(s):  
Economic Development ◽  
Recent Literature ◽  
Authoritarian Regimes ◽  
Short Term ◽  
National Crisis ◽  
Different Types ◽  
Types Of Democracy ◽  
The Face ◽  
Long Term Trends

This chapter focuses on democracies, democratization, and authoritarian regimes. It first considers the two main approaches to analysing the global rise of democracy over the last thirty years: first, long-term trends of modernization, and more specifically economic development, that create preconditions for democracy and opportunities for democratic entrepreneurs; and second, the sequences of more short-term events and actions of key actors at moments of national crisis that have precipitated a democratic transition — also known as ‘transitology’. The chapter proceeds by discussing the different types of democracy and the strategies used to measure democracy. It also reviews the more recent literature on authoritarian systems and why they persist. Finally, it examines the challenges that confront democracy in the face of authoritarian revival.

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