scholarly journals Dynamics and predictability of cold spells over the Eastern Mediterranean

2020 ◽  
Author(s):  
Assaf Hochman ◽  
Sebastian Scher ◽  
Julian Quinting ◽  
Joaquim G. Pinto ◽  
Gabriele Messori

Abstract The accurate prediction of extreme weather events is an important and challenging task, and has typically relied on numerical simulations of the atmosphere. Here, we combine insights from numerical forecasts with recent developments in dynamical systems theory, which describe atmospheric states in terms of their persistence (θ−1) and local dimension (d), and inform on how the atmosphere evolves to and from a given state of interest. These metrics are intuitively linked to the intrinsic predictability of the atmosphere: a highly persistent, low-dimensional state will be more predictable than a low-persistence, high-dimensional one. We argue that θ−1 and d, derived from reanalysis sea level pressure (SLP) and geopotential height (Z500) fields, can provide complementary predictive information for mid-latitude extreme weather events. Specifically, signatures of regional extreme weather events might be reflected in the dynamical systems metrics, even when the actual extreme is not well-simulated in numerical forecasting systems. We focus on cold spells in the Eastern Mediterranean, and particularly those associated with snow cover in Jerusalem. These rare events are systematically associated with Cyprus Lows, which are the dominant rain-bearing weather system in the region. In our analysis, we compare the ‘cold spell Cyprus Lows’ to other ‘regular’ Cyprus Low days. Significant differences are found between cold spells and ‘regular’ Cyprus Lows from a dynamical systems perspective. When considering SLP, the intrinsic predictability of cold spells is lowest hours before the onset of snow. We find that the cyclone’s location, depth and magnitude of air-sea fluxes play an important role in determining its intrinsic predictability. The dynamical systems metrics computed on Z500 display a different temporal evolution to their SLP counterparts, highlighting the different characteristics of the atmospheric flow at the different levels. We conclude that the dynamical systems approach, although sometimes challenging to interpret, can complement conventional numerical forecasts and forecast skill measures, such as model spread and absolute error. This methodology outlines an important avenue for future research, which can potentially be fruitfully applied to other regions and other types of weather extremes.

2020 ◽  
Author(s):  
Assaf Hochman ◽  
Pinhas Alpert ◽  
Hadas Saaroni ◽  
Tzvi Harpaz ◽  
Joaquim G. Pinto ◽  
...  

<p>Extreme weather events have long been considered challenging to predict. It is likely that global warming will trigger extreme weather in many regions of the globe and especially over the Mediterranean ´hot spot´. Therefore, extreme weather events have been selected as one of the grand challenges of the World Climate Research Program.</p><p>The intrinsic predictability of a weather system, or any dynamical system, depends on its persistence and its active number of degrees of freedom. Recent developments in dynamical systems theory allow to compute these metrics for atmospheric configurations (1). In most of the mid-latitudes, synoptic scale patterns exert a strong control on regional weather, thus, stimulating a broad interest, especially in weather forecasting. Recently, we have integrated the dynamical systems approach with a synoptic classification algorithm over the Eastern Mediterranean (2).  It was shown that the dynamical systems perspective provides an extremely informative tool for evaluating the predictability of synoptic patterns and especially of weather extremes.</p><p>The novel perspective, which leverages a dynamical systems approach to investigate the predictability of extreme weather events, outlines a new avenue of research that may be fruitfully applied at operational weather and climate forecasting services in the Mediterranean Region and around the globe.</p><p><strong>References</strong></p><ol><li>Faranda D, Messori G, Yiou P. 2017. Dynamical Proxies of North Atlantic Predictability and Extremes. Scientific Reports <strong>7</strong>, 412782017b. DOI: 10.1038/srep4127</li> <li>Hochman A, Alpert P, Harpaz T, Saaroni H, Messori G. 2019. A New Dynamical Systems Perspective on Atmospheric Predictability; Eastern Mediterranean Weather Regimes as a Case Study. Science Advances <strong>5</strong>. DOI: 10.1126/sciadv.aau0936</li> </ol>


2014 ◽  
Vol 13 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Ian Young ◽  
Ben A. Smith ◽  
Aamir Fazil

Global climate change is expected to impact drinking water quality through multiple weather-related phenomena. We conducted a systematic review and meta-analysis of the relationship between various weather-related variables and the occurrence and concentration of Cryptosporidium and Giardia in fresh surface waters. We implemented a comprehensive search in four databases, screened 1,228 unique citations for relevance, extracted data from 107 relevant articles, and conducted random-effects meta-analysis on 16 key relationships. The average odds of identifying Cryptosporidium oocysts and Giardia cysts in fresh surface waters was 2.61 (95% CI = 1.63–4.21; I2 = 16%) and 2.87 (95% CI = 1.76–4.67; I2 = 0%) times higher, respectively, during and after extreme weather events compared to baseline conditions. Similarly, the average concentration of Cryptosporidium and Giardia identified under these conditions was also higher, by approximately 4.38 oocysts/100 L (95% CI = 2.01–9.54; I2 = 0%) and 2.68 cysts/100 L (95% CI = 1.08–6.55; I2 = 48%). Correlation relationships between other weather-related parameters and the density of these pathogens were frequently heterogeneous and indicated low to moderate effects. Meta-regression analyses identified different study-level factors that influenced the variability in these relationships. The results can be used as direct inputs for quantitative microbial risk assessment. Future research is warranted to investigate these effects and potential mitigation strategies in different settings and contexts.


2019 ◽  
Author(s):  
Suvi Ruuskanen ◽  
Bin-Yan Hsu ◽  
Andreas Nord

The ability to maintain a (relatively) stable body temperature in a wide range of thermal environments is a unique feature of endotherms such as birds. Endothermy is acquired and regulated via various endocrine and molecular pathways, and ultimately allows wide aerial, aquatic, and terrestrial distribution in variable environments. However, due to our changing climate, birds are faced with potential new challenges for thermoregulation, such as more frequent extreme weather events, lower predictability of climate, and increasing mean temperature. We provide a compact overview on thermoregulation in birds and its endocrine and molecular mechanisms, pinpointing gaps in current knowledge and recent developments, focusing especially on non-model species to understand the generality of, and variation in, mechanisms. We highlight plasticity in thermoregulation and underlying endocrine regulation, because thorough understanding of plasticity is key to predicting responses to changing environmental conditions. To this end, we discuss how changing climate is likely to affect avian thermoregulation and associated endocrine traits, and how the interplay between these physiological processes may play a role in facilitating or constraining adaptation to a changing climate. We conclude that while the general patterns of endocrine regulation of thermogenesis are quite well understood, at least in poultry, the molecular and endocrine mechanisms that regulate e.g. mitochondria function and plasticity of thermoregulation over different time scales (from transgenerational to daily variation) need to be unveiled. Plasticity may ameliorate climate change effects on thermoregulation to some extent, but the increased frequency of extreme weather events, and associated in resource availability, may be beyond the scope and/or speed for plastic responses. This could lead to selection for more tolerant phenotypes, if the underlying physiological traits harbour genetic and individual variation for selection to act on – a key question for future research.


2020 ◽  
Author(s):  
Assaf Hochman ◽  
Sebastian Scher ◽  
Julian Quinting ◽  
Joaquim G. Pinto ◽  
Gabriele Messori

Abstract. Skillful forecasts of extreme weather events have a major socio-economic relevance. Here, we compare two complementary approaches to diagnose the predictability of extreme weather: recent developments in dynamical systems theory and numerical ensemble weather forecasts. The former allows us to define atmospheric configurations in terms of their persistence and local dimension, which inform on how the atmosphere evolves to and from a given state of interest. These metrics may be used as proxies for the intrinsic predictability of the atmosphere, which depends exclusively on the atmosphere’s properties. Ensemble weather forecasts inform on the practical predictability of the atmosphere, which primarily depends on the performance of the numerical model used. We focus on heat waves affecting the Eastern Mediterranean. These are identified using the Climatic Stress Index (CSI), which was explicitly developed for the summer weather conditions in this region and differentiates between heat waves (upper decile) and cool days (lower decile). Significant differences are found between the two groups from both the dynamical systems and the numerical weather prediction perspectives. Specifically, heat waves show relatively stable flow characteristics (high intrinsic predictability), but comparatively low practical predictability (large model spread/error). For 500 hPa geopotential height fields, the intrinsic predictability of heat waves is lowest at the event’s onset and decay. We relate these results to the physical processes governing Eastern Mediterranean summer heat waves: adiabatic descent of the air parcels over the region and the geographical origin of the air parcels over land prior to the onset of a heat wave. A detailed analysis of the mid-August 2010 record-breaking heat wave provides further insights into the range of different regional atmospheric configurations conducive to heat waves. We conclude that the dynamical systems approach can be a useful complement to conventional numerical forecasts for understanding the dynamics of Eastern Mediterranean heat waves.


2016 ◽  
Vol 23 (1) ◽  
pp. 59-69 ◽  
Author(s):  
Zbigniew W. Kundzewicz

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.


Author(s):  
Elzbieta M. Bitner-Gregersen ◽  
Torfinn Ho̸rte ◽  
Rolf Skjong

Global warming and extreme weather events reported in the last years have attracted a lot of attention in academia, industry and media. The ongoing debate around the observed climate change has focused on three important questions: will occurrence of extreme weather events increase in the future, which geographical locations will be most affected, and to what degree will climate change have impact on future ship traffic and design of ships and offshore structures? The present study shortly reviews the findings of the Intergovernmental Panel on Climate Change Fourth Assessment Report, AR4, [1] and other relevant publications regarding projections of meteorological and oceanographic conditions in the 21st century and beyond with design needs in focus. Emphasis is on wave climate and its potential implications on safe design and operations of ship structures. A risk based approach for marine structure design accounting for climate change is proposed. The impact of expected wave climate change on ship design is demonstrated for five oil tankers, ranging from Product tanker to VLCC. Consequences of climate change for the hull girder failure probability and hence the steel weight of the deck in the midship region is shown. Recommendations for future research activities allowing adaptation to climate change are given.


MAUSAM ◽  
2021 ◽  
Vol 67 (1) ◽  
pp. 27-52
Author(s):  
L. S. RATHORE ◽  
D. R. PATTANAIK ◽  
S. C. BHAN

Being mainly an agricultural country the economy of India and its growth mainly depends on the vagaries of the weather and in particular the extreme weather events. India with a land of unique climatic regime due to several characteristic features, including (i) two monsoon seasons (south-west and north-east) leading to drought & flood condition, active and break cycle of monsoon and also heavy rainfall leading to flash flood and landslides, (ii) two cyclone seasons (pre and post-monsoon cyclone seasons), (iii) hot weather season characterized by severe thunderstorms, dust storms and heat waves, (iv) cold weather season characterized by violent snow storms in the Himalayan regions, cold waves and fog. The socio-economic impacts of the extreme weather events such as floods, droughts, heavy rainfall, cyclones, hail storm, thunderstorm, heat and cold waves have been increasing due to large growth of population and urbanizations, which has led to greater vulnerability. A spatio-temporal analysis of these weather extremes over India will be very helpful to understand the vulnerability potential and to improve the forecast skill and use these forecasts in minimizing the adverse impacts of such weather extremes. 


2022 ◽  
Author(s):  
Anni Vehola ◽  
Elias Hurmekoski ◽  
Katja Lähtinen ◽  
Enni Ruokamo ◽  
Anders Roos ◽  
...  

Abstract Climate change places great pressure on the construction sector to decrease its greenhouse gas emissions and to create solutions that perform well in changing weather conditions. In the urbanizing world, wood construction has been identified as one of the opportunities for mitigating these emissions. Our study explores citizen opinions on wood usage as a building material under expected mitigation and adaptation measures aimed at a changing climate and extreme weather events. The data are founded on an internet-based survey material collected from a consumer panel from Finland and Sweden during May–June 2021, with a total of 2015 responses. By employing exploratory factor analysis, we identified similar belief structures for the two countries, consisting of both positive and negative views on wood construction. In linear regressions for predicting these opinions, the perceived seriousness of climate change was found to increase positive views on wood construction but was insignificant for negative views. Both in Finland and Sweden, higher familiarity with wooden multistory construction was found to connect with more positive opinions on the potential of wood in building, e.g., due to carbon storage properties and material attributes. Our findings underline the potential of wood material use as one avenue of climate change adaptation in the built environment. Future research should study how citizens’ concerns for extreme weather events affect their future material preferences in their everyday living environments, also beyond the Nordic region.


2018 ◽  
Vol 99 (8) ◽  
pp. 1557-1568 ◽  
Author(s):  
Julien Cattiaux ◽  
Aurélien Ribes

AbstractWeather extremes are the showcase of climate variability. Given their societal and environmental impacts, they are of great public interest. The prevention of natural hazards, the monitoring of single events, and, more recently, their attribution to anthropogenic climate change constitute key challenges for both weather services and scientific communities. Before a single event can be scrutinized, it must be properly defined; in particular, its spatiotemporal characteristics must be chosen. So far, this definition is made with some degree of arbitrariness, yet it might affect conclusions when explaining an extreme weather event from a climate perspective. Here, we propose a generic road map for defining single events as objectively as possible. In particular, as extreme events are inherently characterized by a small probability of occurrence, we suggest selecting the space–time characteristics that minimize this probability. In this way, we are able to automatically identify the spatiotemporal scale at which the event has been the most extreme. According to our methodology, the European heat wave of summer 2003 would be defined as a 2-week event over France and Spain and the Boulder, Colorado, intense rainfall of September 2013 a 5-day local event. Importantly, we show that in both cases, maximizing the rarity of the event does not maximize (or minimize) its fraction of attributable risk to anthropogenic climate change.


Sign in / Sign up

Export Citation Format

Share Document