scholarly journals Extremal dependence as given by the tail pairwise dependence matrix inprecipitation and temperature data

2021 ◽  
Author(s):  
Svenja Szemkus ◽  
Petra Friederichs
Keyword(s):  
Principal Component Analysis ◽  
Spatial Patterns ◽  
Heat Waves ◽  
Principal Component ◽  
Component Analysis ◽  
Extreme Weather ◽  
Temperature Data ◽  
Extreme Weather Events ◽  
Weather Events ◽  
Pairwise Dependence

<p>A better understanding of the dynamics and impacts of extreme weather events and their changes due to climate change is the subject of the ClimXtreme project (climxtreme.net) funded by the German Federal Ministry of Education and Research. <br>The CoDEx project is investigating how data compression techniques can contribute to a better description and understanding of extremes. Various unsupervised learning approaches, such as clustering or principal component analysis, focusing on extremes have been developed recently and will be investigated and compared within the project. <br>We use principal component analysis to study the spatial (co-)occurrence during extreme weather events such as heavy precipitation, heat waves or droughts. The focus on extreme events is done by using the tail pairwise dependence matrix (TPDM), proposed by Cooley and Thibaud (2019) as an analogue to the covariance matrix for extremes. Since the simultaneous occurrence of precipitation deficits and high temperature played an important role, especially in heat waves, we explore how Cooley and Thibaud's concept can be used in this regard. We propose an estimation of the TPDM based on pairwise dependencies of two variables. A singular value decomposition gives us insight into the spatial co-occurrence of extreme spatial patterns, which contributes to the understanding of so-called compound events. <br>We use daily precipitation and temperature data, including observational stations and regional reanalyses in Germany and Europe. Using this method, we extract spatial patterns over Germany and Europe based on extreme dependencies. In addition, we identify historical events, and examine them in more detail in this context.</p>

scholarly journals Impacts of compound extreme weather events on ozone in the present and future

2018 ◽  
Author(s):  
Junxi Zhang ◽  
Yang Gao ◽  
Kun Luo ◽  
L. Ruby Leung ◽  
Yang Zhang ◽  
...  
Keyword(s):  
Extreme Events ◽  
Heat Waves ◽  
Extreme Weather ◽  
Extreme Weather Events ◽  
Low Wind Speed ◽  
Weather Events ◽  
The Us ◽  
The Future ◽  
Compound Events ◽  
Ozone Episodes

Abstract. The Weather Research and Forecasting model with Chemistry (WRF/Chem) was used to study the effect of extreme weather events on ozone in US for historical (2001–2010) and future (2046–2055) periods under RCP8.5 scenario. During extreme weather events, including heat waves, atmospheric stagnation, and their compound events, ozone concentration is much higher compared to non-extreme events period. A striking enhancement of effect during compound events is revealed when heat wave and stagnation occur simultaneously and both high temperature and low wind speed promote the production of high ozone concentrations. In regions with high emissions, compound extreme events can shift the high-end tails of the probability density functions (PDFs) of ozone to even higher values to generate extreme ozone episodes. In regions with low emissions, extreme events can still increase high ozone frequency but the high-end tails of the PDFs are constrained by the low emissions. Despite large anthropogenic emission reduction projected for the future, compound events increase ozone more than the single events by 10 % to 13 %, comparable to the present, and high ozone episodes are not eliminated. Using the CMIP5 multi-model ensemble, the frequency of compound events is found to increase more dominantly compared to the increased frequency of single events in the future over the US, Europe, and China. High ozone episodes will likely continue in the future due to increases in both frequency and intensity of extreme events, despite reductions in anthropogenic emissions of its precursors. However, the latter could reduce or eliminate extreme ozone episodes, so improving projections of compound events and their impacts on extreme ozone may better constrain future projections of extreme ozone episodes that have detrimental effects on human health.

scholarly journals ROCK MAGNETIC AND PALAEOMAGNETIC ANALYSES ON LITHIC FRAGMENTS FROM THE ARCHAEOLOGICAL SITE OF AKROTIRI, SANTORINI

2017 ◽  
Vol 50 (3) ◽  
pp. 1250
Author(s):  
E. Tema
Keyword(s):  
Principal Component Analysis ◽  
Deposition Temperature ◽  
Principal Component ◽  
Archaeological Site ◽  
Equilibrium Temperature ◽  
Component Analysis ◽  
Temperature Data ◽  
Minoan Eruption ◽  
Pumice Fall ◽  
Good Agreement

Rock magnetic and palaeomagnetic analyses on lithic clasts collected from the pumice fall deposited inside the archaeological site of Akrotiri have been applied in order to estimate the deposition temperature of the first volcanic products of the Minoan eruption. A total of 50 lithic clasts have been collected from four different locations inside the excavation of Akrotiri. All samples have been stepwise thermally demagnetized and the obtained results have been interpreted through principal component analysis. The equilibrium temperature obtained after the deposition of the pumice fall varies from sample to sample but generally shows temperatures around 240-280oC. These temperatures are in good agreement with those estimated from lithic clasts from the Megalochori Quarry while they are higher compared with those from ceramic fragments from Akrotiri. The new temperature data presented here show that the pumice fall was still relatively hot when deposited inside the archaeological site and even if it interacted with the buildings, often causing the collapse of roofs, it still remained hot with mean temperature around 260oC.

scholarly journals Extreme Weather Impacts on Inland Waterways Transport of Yangtze River

Atmosphere ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 133 ◽  
Author(s):  
Lijun Liu ◽  
Yuanqiao Wen ◽  
Youjia Liang ◽  
Fan Zhang ◽  
Tiantian Yang
Keyword(s):  
Heat Wave ◽  
Yangtze River ◽  
Heat Waves ◽  
Extreme Weather ◽  
Extreme Weather Events ◽  
The Yangtze River ◽  
Climate Zone ◽  
Inland Waterways ◽  
Weather Events ◽  
The Impact

The impact of extreme weather events on the navigation environment in the inland waterways of the Yangtze River is an interdisciplinary hotspot in subjects of maritime traffic safety and maritime meteorology, and it is also a difficult point for the implementation of decision-making and management by maritime and meteorological departments in China. The objective of this study is to review the variation trends and distribution patterns in the periods of adverse and extreme weather events that are expected to impact on inland waterways transport (IWT) on the Yangtze River. The frequency of severe weather events, together with the changes in their spatial extension and intensity, is analyzed based on the ERA-Interim datasets (1979–2017) and the GHCNDEX dataset (1979–2017), as well as the research progresses and important events (2004–2016) affecting the navigation environment. The impacts of extreme weather events on IWT accidents and phenomena of extreme weather (e.g., thunderstorms, lightning, hail, and tornadoes) that affect the navigation environment are also analyzed and discussed. The results show that: (1) the sections located in the plain climate zone is affected by extreme weather in every season, especially strong winds and heat waves; (2) the sections located in the hilly mountain climate zone is affected particularly by spring extreme phenomena, especially heat waves; (3) the sections located in the Sichuan Basin climate zone is dominated by the extreme weather phenomena in autumn, except cold waves; (4) the occurrence frequency of potential flood risk events is relatively high under rainstorm conditions and wind gusts almost affect the navigation environment of the Jiangsu and Shanghai sections in every year; (5) the heat wave indices (TXx, TR, and WSDI) tend to increase and the temperature of the coldest day of the year gradually increases; (6) the high occurrences of IWT accidents need to be emphasized by relevant departments, caused by extreme weather during the dry season; and (7) the trends and the degree of attention of extreme weather events affecting IWT are ranked as: heat wave > heavy rainfall > wind gust > cold spell > storm. Understanding the seasonal and annual frequency of occurrence of extreme weather events has reference significance for regional management of the Yangtze River.

scholarly journals The impact of two extreme weather events and other causes of death on Carnaby’s Black Cockatoo: a promise of things to come for a threatened species?

2011 ◽  
Vol 17 (2) ◽  
pp. 141 ◽  
Author(s):  
Denis A Saunders ◽  
Peter Mawson ◽  
Rick Dawson
Keyword(s):  
Causes Of Death ◽  
Heat Waves ◽  
Extreme Weather ◽  
Motor Vehicles ◽  
Extreme Weather Events ◽  
Weather Events ◽  
Dramatic Decline ◽  
To Come ◽  
Stochastic Events ◽  
The Impact

Carnaby’s Black Cockatoo is an endangered species which has undergone a dramatic decline in range and abundance in southwestern Australia. Between October 2009 and March 2010 the species was subjected to a possible outbreak of disease in one of its major breeding areas and exposed to an extremely hot day and a severe localized hail storm. In addition, collisions with motor vehicles are becoming an increasing threat to the species. All of these stochastic events resulted in many fatalities. Species such as Carnaby’s Black Cockatoo which form large flocks are particularly susceptible to localized events such as hail storms, contagious disease and collisions with motor vehicles. Extreme temperatures may have major impacts on both flocking and non-flocking species. Predictions of climate change in the southwest of Western Australia are that there will be an increased frequency of extreme weather events such as heat waves and severe hail storms. The implications of more events of this nature on Carnaby’s Black Cockatoo are discussed.

scholarly journals Ondas de calor nas capitais do Sul do Brasil e Montevidéu - Uruguai (Heat waves in the capitals of southern Brazil and Montevideo - Uruguay)

2019 ◽  
Vol 12 (4) ◽  
pp. 1259
Author(s):  
Rafael Brito Silveira ◽  
Maikon Passos Amilton Alves ◽  
Marcelo Barreiro ◽  
Daniel Pires Bitencourt
Keyword(s):  
Heat Wave ◽  
Air Temperature ◽  
Heat Waves ◽  
Kendall Test ◽  
Temperature Data ◽  
Extreme Weather Events ◽  
Southern Brazil ◽  
Porto Alegre ◽  
Significance Level ◽  
Weather Events

Múltiplas partes do globo, possivelmente, passarão a ter dias e noites mais quentes e, com a elevação das temperaturas globais, há tendências de acréscimo do risco de eventos atmosféricos extremos, tais como as ondas de calor. O objetivo principal desse estudo foi verificar as características gerais das ondas de calor nas três capitais da região Sul do Brasil (Curitiba, Florianópolis e Porto Alegre) e também em Montevidéu, capital do Uruguai. Esta análise baseou-se nos parâmetros: frequência, intensidade, duração e suas respectivas tendências. As ondas de calor foram identificadas em uma série de 30 anos de dados diários de temperatura média do ar. As análises de tendência foram averiguadas por meio do teste de Mann-Kendall a um nível de significância de α = 5%. Os resultados mostraram que todos os parâmetros nas quatro cidades apresentam tendências estatisticamente significativas e, com exceção da duração em Montevidéu, todas as demais são positivas. Para além do âmbito das tendências, analisando os parâmetros, comparativamente, conclui-se que Porto Alegre apresenta maior destaque nas médias. Além disto, afirma-se que o inverno é a estação com maior frequência de ondas de calor para todas as cidades.  A B S T R A C TMultiple parts of the globe are likely to have warmer days and nights, and with rising global temperatures, there is a tendency to increase the risk of extreme weather events, such as heat waves. The main objective of this study was to verify the general characteristics of heat waves in the three capitals of southern Brazil (Curitiba, Florianópolis and Porto Alegre) and also in Montevideo, capital of Uruguay. This analysis was based on the parameters: frequency, intensity, duration and their respective trends. Heat waves were identified in a series of 30 years of daily average air temperature data. Trend analyzes were performed using the Mann-Kendall test at a significance level of α = 5%. The results showed that all the parameters in the four cities present statistically significant trends and, except for the duration in Montevideo, all the others are positive. In addition to the scope of the trends, analyzing the parameters, comparatively, it is concluded that Porto Alegre presents greater prominence in the averages. In addition, it is claimed that winter is the season with the highest frequency of heat waves for all cities.Keywords: heat wave, subtropical, capitals, trends, parameters.

scholarly journals Extreme Weather Events and their Consequences

2016 ◽  
Vol 23 (1) ◽  
pp. 59-69 ◽  
Author(s):  
Zbigniew W. Kundzewicz
Keyword(s):  
Forest Fires ◽  
Flood Risk ◽  
Heat Waves ◽  
Extreme Weather ◽  
Extreme Weather Events ◽  
Climate Projections ◽  
Ageing Population ◽  
Weather Extremes ◽  
Weather Events ◽  
Increased Risk

Abstract The damage (in real terms after adjusting for inflation) caused by extreme weather events globally has increased dramatically over the past few decades. This is a result of an increase in the amplitude and frequency of weather extremes, as well as of human factors causing a widespread increase in levels of exposure and vulnerability. There are a number of reasons to consider that, in many regions of the globe, weather extremes (e.g. heat waves, droughts, forest fires, intense rainfall, floods and landslides) are becoming both yet more extreme and more frequent. Projections for the future based on climate and impact models point to a further strengthening of this trend. There has already been an increase in rainfall intensity in conditions of a warmer climate, and a continuation of this trend is expected, with adverse consequences for flood risk. However, the development of flood-prone areas and increase in damage potential are often the dominant factors underpinning growing flood damage and flood risk. In warmer climates, an increased risk of river and flash flooding caused by heavy rainfall, as well as an increasing risk of coastal flooding associated with sea level rise can be expected over large areas. By the same token, a reduction in the risk of snowmelt flooding events is projected in the warmer climate. Projections also indicate an increased risk of drought in many areas. The projections for climate change in Poland point to several risks associated with an increase in the frequency, intensity and severity of weather extremes (heat waves, intensive rainfall, flooding and landslides, coastal surges, drought during the growing season and winter, strong winds and pathogens associated with warming). Heat waves will become more frequent, more intense and more troublesome for the ageing population of Poland.

scholarly journals Reliability Framework for Characterizing Heat Wave and Cold Spell Events

2021 ◽  
Author(s):  
Sanaz Moghim ◽  
Mohammad Sina Jahangir
Keyword(s):  
Heat Wave ◽  
Heat Waves ◽  
Probability Distributions ◽  
Extreme Temperature ◽  
Extreme Weather ◽  
Extreme Weather Events ◽  
Average Intensity ◽  
Cold Spell ◽  
Weather Events ◽  
Two Cities

Abstract Extreme weather events such as heat waves and cold spells affect people’s lives. This study uses a probabilistic framework to evaluate heat waves and cold spells in different regions (Tehran in Iran and Vancouver in Canada). Average daily temperatures of meteorological stations of the two cities from 1995 to 2016 are used to identify four main indicators including intensity, average intensity, duration, and the rate of the occurrence. In addition, average intensities of the events are obtained from the MODIS Land Surface Temperature (LST) in each pixel of the two cities. To include possible uncertainties, the predictive probability distributions of the intensity and duration are derived using a Bayesian scheme and Monte-Carlo Markov Chain (MCMC) method. The probability distributions of the indicators show that the most extreme temperature (lowest temperature) occurs during the cold spell. Results indicate that although Tehran is more probable to experience heat waves than Vancouver, both cities are more likely to be affected by the cold spell than the heat wave. The developed approach can be used to characterize other extreme weather events in any location.

scholarly journals Impacts of compound extreme weather events on ozone in the present and future

2018 ◽  
Vol 18 (13) ◽  
pp. 9861-9877 ◽  
Author(s):  
Junxi Zhang ◽  
Yang Gao ◽  
Kun Luo ◽  
L. Ruby Leung ◽  
Yang Zhang ◽  
...  
Keyword(s):  
Ozone Concentration ◽  
Extreme Events ◽  
Heat Waves ◽  
Extreme Weather ◽  
Extreme Weather Events ◽  
Weather Events ◽  
The Us ◽  
The Future ◽  
Compound Events ◽  
Ozone Episodes

Abstract. The Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) was used to study the effect of extreme weather events on ozone in the US for historical (2001–2010) and future (2046–2055) periods under the RCP8.5 scenario. During extreme weather events, including heat waves, atmospheric stagnation, and their compound events, ozone concentration is much higher compared to the non-extreme events period. A striking enhancement of effect during compound events is revealed when heat wave and stagnation occur simultaneously as both high temperature and low wind speed promote the production of high ozone concentrations. In regions with high emissions, compound extreme events can shift the high-end tails of the probability density functions (PDFs) of ozone to even higher values to generate extreme ozone episodes. In regions with low emissions, extreme events can still increase high-ozone frequency but the high-end tails of the PDFs are constrained by the low emissions. Despite the large anthropogenic emission reduction projected for the future, compound events increase ozone more than the single events by 10 to 13 %, comparable to the present, and high-ozone episodes with a maximum daily 8 h average (MDA8) ozone concentration over 70 ppbv are not eliminated. Using the CMIP5 multi-model ensemble, the frequency of compound events is found to increase more dominantly compared to the increased frequency of single events in the future over the US, Europe, and China. High-ozone episodes will likely continue in the future due to increases in both frequency and intensity of extreme events, despite reductions in anthropogenic emissions of its precursors. However, the latter could reduce or eliminate extreme ozone episodes; thus improving projections of compound events and their impacts on extreme ozone may better constrain future projections of extreme ozone episodes that have detrimental effects on human health.

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